From f2a7652abab5d03f846f3150f9cc1b2dc23bb3dd Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <m@mitchellh.com>
Date: Mon, 20 Jul 2026 20:33:23 -0700
Subject: [PATCH] mitchell's touchups

- benchmark: avoid buffers to avoid a memcpy
- build: keep frame pointers on macOS. There was some debug changes from
  Zig 0.15 and this helps. Also, Apple actually requires/expects x29 to
  always be a frame pointer.
- build/macos: force libSystem symbols instead of compiler-rt
- global: add InitOpts.tool so that ghostty-gen/bench can parse their
  own actions in `+action`
- quirks: provide our own vectorized memset. see the comment for more
  details why.
- synthetic: fix UB by accessing global.io before it was initialized
- terminal/hash_map: force inline for unique repr types. Zig 0.15
  inlined and 0.16 doesn't, measured a huge slowdown in hyperlink
  benchmarks.
- terminal: add explicit `@Vector` usage for storing a run of identical cells
  as well as for scanning printable cells. This auto-vectorized in Zig
  0.15 but not in Zig 0.16. This produces the same assembly.
- unicode: properties and LUT need power-of-two backing integer to avoid
  bad LLVM codegen
---
 .gitignore                          |   2 +-
 build.zig.zon                       |  22 +-
 build.zig.zon.json                  |  32 +--
 build.zig.zon.nix                   |  40 ++--
 build.zig.zon.txt                   |  24 +--
 flatpak/zig-packages.json           |  34 +--
 nix/build-support/update-mirror.nu  |  59 +++--
 pkg/dcimgui/build.zig.zon           |   2 +-
 pkg/gtk4-layer-shell/build.zig.zon  |   2 +-
 pkg/harfbuzz/build.zig.zon          |   2 +-
 pkg/macos/build.zig.zon             |   2 +-
 pkg/wuffs/build.zig.zon             |   2 +-
 src/benchmark/TerminalStream.zig    |   6 +-
 src/benchmark/cli.zig               |   2 +-
 src/build/Config.zig                |  11 +
 src/build/GhosttyExe.zig            |   2 +-
 src/build/GhosttyLib.zig            |  20 +-
 src/build/GhosttyLibVt.zig          |  31 ++-
 src/build/LibsystemOverrideStep.zig |  51 +++++
 src/build/libsystem_override.sh     | 123 +++++++++++
 src/config/path.zig                 |   4 +-
 src/global.zig                      |  27 ++-
 src/lib_vt.zig                      |   6 +
 src/main.zig                        |   7 +
 src/main_bench.zig                  |   6 +
 src/main_c.zig                      |   4 +
 src/main_gen.zig                    |   6 +
 src/quirks_memset.zig               | 322 ++++++++++++++++++++++++++++
 src/simd/main.zig                   |  12 ++
 src/synthetic/cli.zig               |   3 +-
 src/terminal/Terminal.zig           | 155 +++++++++++--
 src/terminal/hash_map.zig           |  18 +-
 src/terminal/stream.zig             |  24 ++-
 src/unicode/grapheme.zig            |  12 +-
 src/unicode/props.zig               |  12 +-
 35 files changed, 936 insertions(+), 151 deletions(-)
 create mode 100644 src/build/LibsystemOverrideStep.zig
 create mode 100755 src/build/libsystem_override.sh
 create mode 100644 src/quirks_memset.zig

diff --git a/.gitignore b/.gitignore
index 51b929544..c60d3bb15 100644
--- a/.gitignore
+++ b/.gitignore
@@ -14,7 +14,7 @@ zig-pkg/
 build-cmake/
 CMakeCache.txt
 CMakeFiles/
-/build.zig.zon.bak
+build.zig.zon.bak
 /result*
 /.nixos-test-history
 example/*.wasm
diff --git a/build.zig.zon b/build.zig.zon
index 8d1553199..6f8287505 100644
--- a/build.zig.zon
+++ b/build.zig.zon
@@ -11,62 +11,62 @@
         // Aro/translate-c itself.
         .translate_c = .{
             .lazy = true,
-            .url = "https://codeberg.org/vancluever/translate-c/archive/a916baf225a3cfc93a982225462db612604ae290.tar.gz",
+            .url = "https://deps.files.ghostty.org/translate_c-a916baf225a3cfc93a982225462db612604ae290.tar.gz",
             .hash = "translate_c-0.0.0-Q_BUWj8_BwCr4na219OimiKKj4IVSq0aKtMXCQmIk4AB",
         },
 
         // Zig libs
         .libxev = .{
             // mitchellh/libxev
-            .url = "https://github.com/mitchellh/libxev/archive/9ce8e8e6ff89e583258a7f8e7adeeeaeae8611bf.tar.gz",
+            .url = "https://deps.files.ghostty.org/libxev-9ce8e8e6ff89e583258a7f8e7adeeeaeae8611bf.tar.gz",
             .hash = "libxev-0.0.0-86vtcwIRFADbH4hk-EjROXxlrKIRPQdA41XiTSytYO-F",
             .lazy = true,
         },
         .vaxis = .{
             // rockorager/libvaxis
-            .url = "https://github.com/rockorager/libvaxis/archive/1dbbe575dff4586fe51e3217aa5c3fecdcbb6089.tar.gz",
+            .url = "https://deps.files.ghostty.org/vaxis-1dbbe575dff4586fe51e3217aa5c3fecdcbb6089.tar.gz",
             .hash = "vaxis-0.6.0-BWNV_CrbCQCscGpzsAlR402rYQ_tV3aAl081c2iRRkka",
             .lazy = true,
         },
         .z2d = .{
             // vancluever/z2d
-            .url = "https://github.com/vancluever/z2d/archive/refs/tags/v0.11.0.tar.gz",
+            .url = "https://deps.files.ghostty.org/z2d-0.11.0-j5P_HtLzDwBGyQt49DrT0v4BuVqI_SRs6CXsuj7eBVhR.tar.gz",
             .hash = "z2d-0.11.0-j5P_HtLzDwBGyQt49DrT0v4BuVqI_SRs6CXsuj7eBVhR",
             .lazy = true,
         },
         .zig_objc = .{
             // mitchellh/zig-objc
-            .url = "https://github.com/mitchellh/zig-objc/archive/c8de82ff80281215ad92900866dab7103a8efa8b.tar.gz",
+            .url = "https://deps.files.ghostty.org/zig_objc-c8de82ff80281215ad92900866dab7103a8efa8b.tar.gz",
             .hash = "zig_objc-0.0.0-Ir_Sp9gsAQCPAJc0oF5xoWePHWP6Y6tCphDeyNUThJoi",
             .lazy = true,
         },
         .zig_js = .{
             // mitchellh/zig-js
-            .url = "https://github.com/mitchellh/zig-js/archive/3c23860e47fdcdc5af805efb7fd0bdac5fd3e9bc.tar.gz",
+            .url = "https://deps.files.ghostty.org/zig_js-3c23860e47fdcdc5af805efb7fd0bdac5fd3e9bc.tar.gz",
             .hash = "zig_js-0.0.0-rjCAV7-GAADvMTBL7lPMuvDk7xgS9PCMIZWiOUXLZSlj",
             .lazy = true,
         },
         .uucode = .{
             // jacobsandlund/uucode
-            .url = "https://github.com/jacobsandlund/uucode/archive/2826a37a4562284fdacd8fa029d49509cc9bffcd.tar.gz",
+            .url = "https://deps.files.ghostty.org/uucode-2826a37a4562284fdacd8fa029d49509cc9bffcd.tar.gz",
             .hash = "uucode-0.2.0-ZZjBPlK5VADj7fdoq7G8LIHzD5o6FSkcBXXrRWr4jnrA",
         },
         .zig_wayland = .{
             // codeberg ifreund/zig-wayland
-            .url = "https://codeberg.org/ifreund/zig-wayland/archive/v0.6.0.tar.gz",
+            .url = "https://deps.files.ghostty.org/wayland-0.6.0-lQa1kqz8AQADQmdNJsNhLoNHcnEGEUjrOaPV-dtEnEmX.tar.gz",
             .hash = "wayland-0.6.0-lQa1kqz8AQADQmdNJsNhLoNHcnEGEUjrOaPV-dtEnEmX",
             .lazy = true,
         },
         .zf = .{
             // natecraddock/zf
-            .url = "https://github.com/natecraddock/zf/archive/c35c421f84895193246db06c40683c1a30e616ef.tar.gz",
+            .url = "https://deps.files.ghostty.org/zf-c35c421f84895193246db06c40683c1a30e616ef.tar.gz",
             .hash = "zf-0.11.0-OIRy8X-RAAAwaRXHMYpj2uvBnuGTZWEE_3V7acqHQNtW",
             .lazy = true,
         },
         .gobject = .{
             // https://github.com/ghostty-org/zig-gobject based on zig_gobject
             // Temporary until we generate them at build time automatically.
-            .url = "https://github.com/ghostty-org/zig-gobject/releases/download/0.8.0-2026-04-23-26-1/ghostty-gobject-0.8.0-2026-04-23-26-1.tar.zst",
+            .url = "https://deps.files.ghostty.org/gobject-2026-04-23-26-1.tar.zst",
             .hash = "gobject-0.3.1-Skun7E1KnwBGMX5nslHYG1yWHaSevywxQO8oM7tTOgIp",
             .lazy = true,
         },
@@ -99,7 +99,7 @@
             .lazy = true,
         },
         .wayland_protocols = .{
-            .url = "https://gitlab.freedesktop.org/wayland/wayland-protocols/-/archive/1.47/wayland-protocols-1.47.tar.gz",
+            .url = "https://deps.files.ghostty.org/N-V-__8AAFdWDwA0ktbNUi9pFBHCRN4weXIgIfCrVjfGxqgA.tar.gz",
             .hash = "N-V-__8AAFdWDwA0ktbNUi9pFBHCRN4weXIgIfCrVjfGxqgA",
             .lazy = true,
         },
diff --git a/build.zig.zon.json b/build.zig.zon.json
index 2ca7b1034..e23b6f873 100644
--- a/build.zig.zon.json
+++ b/build.zig.zon.json
@@ -36,7 +36,7 @@
   },
   "gobject-0.3.1-Skun7E1KnwBGMX5nslHYG1yWHaSevywxQO8oM7tTOgIp": {
     "name": "gobject",
-    "url": "https://github.com/ghostty-org/zig-gobject/releases/download/0.8.0-2026-04-23-26-1/ghostty-gobject-0.8.0-2026-04-23-26-1.tar.zst",
+    "url": "https://deps.files.ghostty.org/gobject-2026-04-23-26-1.tar.zst",
     "hash": "sha256-cZGf9a1+sDeORKWYIdzQ/5KLT7l/9pgPc2cIbqfBc4o="
   },
   "N-V-__8AALiNBAA-_0gprYr92CjrMj1I5bqNu0TSJOnjFNSr": {
@@ -56,7 +56,7 @@
   },
   "N-V-__8AAEbOfQBnvcFcCX2W5z7tDaN8vaNZGamEQtNOe0UI": {
     "name": "imgui",
-    "url": "https://github.com/ocornut/imgui/archive/refs/tags/v1.92.5-docking.tar.gz",
+    "url": "https://deps.files.ghostty.org/N-V-__8AAEbOfQBnvcFcCX2W5z7tDaN8vaNZGamEQtNOe0UI.tar.gz",
     "hash": "sha256-yBbCDox18+Fa6Gc1DnmSVQLRpqhZOLsac7iSfl8x+cs="
   },
   "N-V-__8AALZGBAAS5NLVH-c8eC-6VtCdcH-9nUvVfUSkWS__": {
@@ -76,7 +76,7 @@
   },
   "libxev-0.0.0-86vtcwIRFADbH4hk-EjROXxlrKIRPQdA41XiTSytYO-F": {
     "name": "libxev",
-    "url": "https://github.com/mitchellh/libxev/archive/9ce8e8e6ff89e583258a7f8e7adeeeaeae8611bf.tar.gz",
+    "url": "https://deps.files.ghostty.org/libxev-9ce8e8e6ff89e583258a7f8e7adeeeaeae8611bf.tar.gz",
     "hash": "sha256-fOU1oxIxfoEgoLuWz7fVX6M+zmqpo7gqZObWiH/aDE0="
   },
   "N-V-__8AAG3RoQEyRC2Vw7Qoro5SYBf62IHn3HjqtNVY6aWK": {
@@ -116,12 +116,12 @@
   },
   "translate_c-0.0.0-Q_BUWj8_BwCr4na219OimiKKj4IVSq0aKtMXCQmIk4AB": {
     "name": "translate_c",
-    "url": "https://codeberg.org/vancluever/translate-c/archive/a916baf225a3cfc93a982225462db612604ae290.tar.gz",
+    "url": "https://deps.files.ghostty.org/translate_c-a916baf225a3cfc93a982225462db612604ae290.tar.gz",
     "hash": "sha256-i7TSSiLU9YGtLtEjgVqy2jSnKLDTeKHX+EFuXEMXJ+U="
   },
   "uucode-0.2.0-ZZjBPlK5VADj7fdoq7G8LIHzD5o6FSkcBXXrRWr4jnrA": {
     "name": "uucode",
-    "url": "https://github.com/jacobsandlund/uucode/archive/2826a37a4562284fdacd8fa029d49509cc9bffcd.tar.gz",
+    "url": "https://deps.files.ghostty.org/uucode-2826a37a4562284fdacd8fa029d49509cc9bffcd.tar.gz",
     "hash": "sha256-R5RXW5tWIaDq5JOF2+oWd5YOYOyns6WH7f687WE+b20="
   },
   "vaxis-0.6.0-BWNV_MjFCQCs9UDHiRkrgw_ayeiPkzOe4xVbaAqXkUWW": {
@@ -131,7 +131,7 @@
   },
   "vaxis-0.6.0-BWNV_CrbCQCscGpzsAlR402rYQ_tV3aAl081c2iRRkka": {
     "name": "vaxis",
-    "url": "https://github.com/rockorager/libvaxis/archive/1dbbe575dff4586fe51e3217aa5c3fecdcbb6089.tar.gz",
+    "url": "https://deps.files.ghostty.org/vaxis-1dbbe575dff4586fe51e3217aa5c3fecdcbb6089.tar.gz",
     "hash": "sha256-z3J3w+oYapfAZZR+MvWXwg+th1hePDA1TptnKFO4r+M="
   },
   "N-V-__8AAKrHGAAs2shYq8UkE6bGcR1QJtLTyOE_lcosMn6t": {
@@ -139,16 +139,16 @@
     "url": "https://deps.files.ghostty.org/wayland-9cb3d7aa9dc995ffafdbdef7ab86a949d0fb0e7d.tar.gz",
     "hash": "sha256-6kGR1o5DdnflHzqs3ieCmBAUTpMdOXoyfcYDXiw5xQ0="
   },
+  "N-V-__8AAFdWDwA0ktbNUi9pFBHCRN4weXIgIfCrVjfGxqgA": {
+    "name": "wayland_protocols",
+    "url": "https://deps.files.ghostty.org/N-V-__8AAFdWDwA0ktbNUi9pFBHCRN4weXIgIfCrVjfGxqgA.tar.gz",
+    "hash": "sha256-3S3xSrX0EDgleq7cxLX7msDuAY8/D5SvkJcCjmDTMiM="
+  },
   "N-V-__8AAKw-DAAaV8bOAAGqA0-oD7o-HNIlPFYKRXSPT03S": {
     "name": "wayland_protocols",
     "url": "https://deps.files.ghostty.org/wayland-protocols-258d8f88f2c8c25a830c6316f87d23ce1a0f12d9.tar.gz",
     "hash": "sha256-XO3K3egbdeYPI+XoO13SuOtO+5+Peb16NH0UiusFMPg="
   },
-  "N-V-__8AAFdWDwA0ktbNUi9pFBHCRN4weXIgIfCrVjfGxqgA": {
-    "name": "wayland_protocols",
-    "url": "https://gitlab.freedesktop.org/wayland/wayland-protocols/-/archive/1.47/wayland-protocols-1.47.tar.gz",
-    "hash": "sha256-3S3xSrX0EDgleq7cxLX7msDuAY8/D5SvkJcCjmDTMiM="
-  },
   "N-V-__8AAAzZywE3s51XfsLbP9eyEw57ae9swYB9aGB6fCMs": {
     "name": "wuffs",
     "url": "https://deps.files.ghostty.org/wuffs-122037b39d577ec2db3fd7b2130e7b69ef6cc1807d68607a7c232c958315d381b5cd.tar.gz",
@@ -156,27 +156,27 @@
   },
   "z2d-0.11.0-j5P_HtLzDwBGyQt49DrT0v4BuVqI_SRs6CXsuj7eBVhR": {
     "name": "z2d",
-    "url": "https://github.com/vancluever/z2d/archive/refs/tags/v0.11.0.tar.gz",
+    "url": "https://deps.files.ghostty.org/z2d-0.11.0-j5P_HtLzDwBGyQt49DrT0v4BuVqI_SRs6CXsuj7eBVhR.tar.gz",
     "hash": "sha256-/Yje2P+ro7IrPodQ26YKk7RsPSYj1Cqx6bdrmykXEKA="
   },
   "zf-0.11.0-OIRy8X-RAAAwaRXHMYpj2uvBnuGTZWEE_3V7acqHQNtW": {
     "name": "zf",
-    "url": "https://github.com/natecraddock/zf/archive/c35c421f84895193246db06c40683c1a30e616ef.tar.gz",
+    "url": "https://deps.files.ghostty.org/zf-c35c421f84895193246db06c40683c1a30e616ef.tar.gz",
     "hash": "sha256-LHurWwqK8jhP8AZd/CXrMJNeVsKftRCTN31/EgEgKaA="
   },
   "zig_js-0.0.0-rjCAV7-GAADvMTBL7lPMuvDk7xgS9PCMIZWiOUXLZSlj": {
     "name": "zig_js",
-    "url": "https://github.com/mitchellh/zig-js/archive/3c23860e47fdcdc5af805efb7fd0bdac5fd3e9bc.tar.gz",
+    "url": "https://deps.files.ghostty.org/zig_js-3c23860e47fdcdc5af805efb7fd0bdac5fd3e9bc.tar.gz",
     "hash": "sha256-Q1643wb/MCX0QkPa9QEY9xeQbqpC2IOrjER0ZyL3mH0="
   },
   "zig_objc-0.0.0-Ir_Sp9gsAQCPAJc0oF5xoWePHWP6Y6tCphDeyNUThJoi": {
     "name": "zig_objc",
-    "url": "https://github.com/mitchellh/zig-objc/archive/c8de82ff80281215ad92900866dab7103a8efa8b.tar.gz",
+    "url": "https://deps.files.ghostty.org/zig_objc-c8de82ff80281215ad92900866dab7103a8efa8b.tar.gz",
     "hash": "sha256-t8cTTJm0crcoGAyOqXO0wB2w7Yit80J2Orwr6prd/G0="
   },
   "wayland-0.6.0-lQa1kqz8AQADQmdNJsNhLoNHcnEGEUjrOaPV-dtEnEmX": {
     "name": "zig_wayland",
-    "url": "https://codeberg.org/ifreund/zig-wayland/archive/v0.6.0.tar.gz",
+    "url": "https://deps.files.ghostty.org/wayland-0.6.0-lQa1kqz8AQADQmdNJsNhLoNHcnEGEUjrOaPV-dtEnEmX.tar.gz",
     "hash": "sha256-3m/ITNhZUJ/5uD/Tqm+0uZSktGoYgWF5oldOqOCUkIE="
   },
   "zigimg-0.1.0-8_eo2oyaFwBZwJpmqPkCfVXWBrHcqbYwmrp1I6bTD3lI": {
diff --git a/build.zig.zon.nix b/build.zig.zon.nix
index 2dec71387..cfda6af29 100644
--- a/build.zig.zon.nix
+++ b/build.zig.zon.nix
@@ -164,7 +164,7 @@ in
       name = "gobject-0.3.1-Skun7E1KnwBGMX5nslHYG1yWHaSevywxQO8oM7tTOgIp";
       path = fetchZigArtifact {
         name = "gobject";
-        url = "https://github.com/ghostty-org/zig-gobject/releases/download/0.8.0-2026-04-23-26-1/ghostty-gobject-0.8.0-2026-04-23-26-1.tar.zst";
+        url = "https://deps.files.ghostty.org/gobject-2026-04-23-26-1.tar.zst";
         hash = "sha256-cZGf9a1+sDeORKWYIdzQ/5KLT7l/9pgPc2cIbqfBc4o=";
         unpack = true;
       };
@@ -200,7 +200,7 @@ in
       name = "N-V-__8AAEbOfQBnvcFcCX2W5z7tDaN8vaNZGamEQtNOe0UI";
       path = fetchZigArtifact {
         name = "imgui";
-        url = "https://github.com/ocornut/imgui/archive/refs/tags/v1.92.5-docking.tar.gz";
+        url = "https://deps.files.ghostty.org/N-V-__8AAEbOfQBnvcFcCX2W5z7tDaN8vaNZGamEQtNOe0UI.tar.gz";
         hash = "sha256-yBbCDox18+Fa6Gc1DnmSVQLRpqhZOLsac7iSfl8x+cs=";
         unpack = false;
       };
@@ -236,7 +236,7 @@ in
       name = "libxev-0.0.0-86vtcwIRFADbH4hk-EjROXxlrKIRPQdA41XiTSytYO-F";
       path = fetchZigArtifact {
         name = "libxev";
-        url = "https://github.com/mitchellh/libxev/archive/9ce8e8e6ff89e583258a7f8e7adeeeaeae8611bf.tar.gz";
+        url = "https://deps.files.ghostty.org/libxev-9ce8e8e6ff89e583258a7f8e7adeeeaeae8611bf.tar.gz";
         hash = "sha256-fOU1oxIxfoEgoLuWz7fVX6M+zmqpo7gqZObWiH/aDE0=";
         unpack = true;
       };
@@ -308,7 +308,7 @@ in
       name = "translate_c-0.0.0-Q_BUWj8_BwCr4na219OimiKKj4IVSq0aKtMXCQmIk4AB";
       path = fetchZigArtifact {
         name = "translate_c";
-        url = "https://codeberg.org/vancluever/translate-c/archive/a916baf225a3cfc93a982225462db612604ae290.tar.gz";
+        url = "https://deps.files.ghostty.org/translate_c-a916baf225a3cfc93a982225462db612604ae290.tar.gz";
         hash = "sha256-i7TSSiLU9YGtLtEjgVqy2jSnKLDTeKHX+EFuXEMXJ+U=";
         unpack = true;
       };
@@ -317,7 +317,7 @@ in
       name = "uucode-0.2.0-ZZjBPlK5VADj7fdoq7G8LIHzD5o6FSkcBXXrRWr4jnrA";
       path = fetchZigArtifact {
         name = "uucode";
-        url = "https://github.com/jacobsandlund/uucode/archive/2826a37a4562284fdacd8fa029d49509cc9bffcd.tar.gz";
+        url = "https://deps.files.ghostty.org/uucode-2826a37a4562284fdacd8fa029d49509cc9bffcd.tar.gz";
         hash = "sha256-R5RXW5tWIaDq5JOF2+oWd5YOYOyns6WH7f687WE+b20=";
         unpack = true;
       };
@@ -335,7 +335,7 @@ in
       name = "vaxis-0.6.0-BWNV_CrbCQCscGpzsAlR402rYQ_tV3aAl081c2iRRkka";
       path = fetchZigArtifact {
         name = "vaxis";
-        url = "https://github.com/rockorager/libvaxis/archive/1dbbe575dff4586fe51e3217aa5c3fecdcbb6089.tar.gz";
+        url = "https://deps.files.ghostty.org/vaxis-1dbbe575dff4586fe51e3217aa5c3fecdcbb6089.tar.gz";
         hash = "sha256-z3J3w+oYapfAZZR+MvWXwg+th1hePDA1TptnKFO4r+M=";
         unpack = true;
       };
@@ -349,6 +349,15 @@ in
         unpack = false;
       };
     }
+    {
+      name = "N-V-__8AAFdWDwA0ktbNUi9pFBHCRN4weXIgIfCrVjfGxqgA";
+      path = fetchZigArtifact {
+        name = "wayland_protocols";
+        url = "https://deps.files.ghostty.org/N-V-__8AAFdWDwA0ktbNUi9pFBHCRN4weXIgIfCrVjfGxqgA.tar.gz";
+        hash = "sha256-3S3xSrX0EDgleq7cxLX7msDuAY8/D5SvkJcCjmDTMiM=";
+        unpack = false;
+      };
+    }
     {
       name = "N-V-__8AAKw-DAAaV8bOAAGqA0-oD7o-HNIlPFYKRXSPT03S";
       path = fetchZigArtifact {
@@ -358,15 +367,6 @@ in
         unpack = false;
       };
     }
-    {
-      name = "N-V-__8AAFdWDwA0ktbNUi9pFBHCRN4weXIgIfCrVjfGxqgA";
-      path = fetchZigArtifact {
-        name = "wayland_protocols";
-        url = "https://gitlab.freedesktop.org/wayland/wayland-protocols/-/archive/1.47/wayland-protocols-1.47.tar.gz";
-        hash = "sha256-3S3xSrX0EDgleq7cxLX7msDuAY8/D5SvkJcCjmDTMiM=";
-        unpack = false;
-      };
-    }
     {
       name = "N-V-__8AAAzZywE3s51XfsLbP9eyEw57ae9swYB9aGB6fCMs";
       path = fetchZigArtifact {
@@ -380,7 +380,7 @@ in
       name = "z2d-0.11.0-j5P_HtLzDwBGyQt49DrT0v4BuVqI_SRs6CXsuj7eBVhR";
       path = fetchZigArtifact {
         name = "z2d";
-        url = "https://github.com/vancluever/z2d/archive/refs/tags/v0.11.0.tar.gz";
+        url = "https://deps.files.ghostty.org/z2d-0.11.0-j5P_HtLzDwBGyQt49DrT0v4BuVqI_SRs6CXsuj7eBVhR.tar.gz";
         hash = "sha256-/Yje2P+ro7IrPodQ26YKk7RsPSYj1Cqx6bdrmykXEKA=";
         unpack = true;
       };
@@ -389,7 +389,7 @@ in
       name = "zf-0.11.0-OIRy8X-RAAAwaRXHMYpj2uvBnuGTZWEE_3V7acqHQNtW";
       path = fetchZigArtifact {
         name = "zf";
-        url = "https://github.com/natecraddock/zf/archive/c35c421f84895193246db06c40683c1a30e616ef.tar.gz";
+        url = "https://deps.files.ghostty.org/zf-c35c421f84895193246db06c40683c1a30e616ef.tar.gz";
         hash = "sha256-LHurWwqK8jhP8AZd/CXrMJNeVsKftRCTN31/EgEgKaA=";
         unpack = true;
       };
@@ -398,7 +398,7 @@ in
       name = "zig_js-0.0.0-rjCAV7-GAADvMTBL7lPMuvDk7xgS9PCMIZWiOUXLZSlj";
       path = fetchZigArtifact {
         name = "zig_js";
-        url = "https://github.com/mitchellh/zig-js/archive/3c23860e47fdcdc5af805efb7fd0bdac5fd3e9bc.tar.gz";
+        url = "https://deps.files.ghostty.org/zig_js-3c23860e47fdcdc5af805efb7fd0bdac5fd3e9bc.tar.gz";
         hash = "sha256-Q1643wb/MCX0QkPa9QEY9xeQbqpC2IOrjER0ZyL3mH0=";
         unpack = true;
       };
@@ -407,7 +407,7 @@ in
       name = "zig_objc-0.0.0-Ir_Sp9gsAQCPAJc0oF5xoWePHWP6Y6tCphDeyNUThJoi";
       path = fetchZigArtifact {
         name = "zig_objc";
-        url = "https://github.com/mitchellh/zig-objc/archive/c8de82ff80281215ad92900866dab7103a8efa8b.tar.gz";
+        url = "https://deps.files.ghostty.org/zig_objc-c8de82ff80281215ad92900866dab7103a8efa8b.tar.gz";
         hash = "sha256-t8cTTJm0crcoGAyOqXO0wB2w7Yit80J2Orwr6prd/G0=";
         unpack = true;
       };
@@ -416,7 +416,7 @@ in
       name = "wayland-0.6.0-lQa1kqz8AQADQmdNJsNhLoNHcnEGEUjrOaPV-dtEnEmX";
       path = fetchZigArtifact {
         name = "zig_wayland";
-        url = "https://codeberg.org/ifreund/zig-wayland/archive/v0.6.0.tar.gz";
+        url = "https://deps.files.ghostty.org/wayland-0.6.0-lQa1kqz8AQADQmdNJsNhLoNHcnEGEUjrOaPV-dtEnEmX.tar.gz";
         hash = "sha256-3m/ITNhZUJ/5uD/Tqm+0uZSktGoYgWF5oldOqOCUkIE=";
         unpack = true;
       };
diff --git a/build.zig.zon.txt b/build.zig.zon.txt
index 1e9505feb..dc0010aab 100644
--- a/build.zig.zon.txt
+++ b/build.zig.zon.txt
@@ -1,9 +1,9 @@
 git+https://github.com/rockorager/libvaxis.git#c1e1f23be38951c425cdf31af455ba23ef178940
 git+https://github.com/zigimg/zigimg#d695acd97c02e57bb151e8f659d1280f5cd6ca70
-https://codeberg.org/ifreund/zig-wayland/archive/v0.6.0.tar.gz
-https://codeberg.org/vancluever/translate-c/archive/a916baf225a3cfc93a982225462db612604ae290.tar.gz
 https://deps.files.ghostty.org/DearBindings_v0.17_ImGui_v1.92.5-docking.tar.gz
 https://deps.files.ghostty.org/JetBrainsMono-2.304.tar.gz
+https://deps.files.ghostty.org/N-V-__8AAEbOfQBnvcFcCX2W5z7tDaN8vaNZGamEQtNOe0UI.tar.gz
+https://deps.files.ghostty.org/N-V-__8AAFdWDwA0ktbNUi9pFBHCRN4weXIgIfCrVjfGxqgA.tar.gz
 https://deps.files.ghostty.org/NerdFontsSymbolsOnly-3.4.0.tar.gz
 https://deps.files.ghostty.org/breakpad-b99f444ba5f6b98cac261cbb391d8766b34a5918.tar.gz
 https://deps.files.ghostty.org/fontconfig-2.14.2.tar.gz
@@ -11,28 +11,28 @@ https://deps.files.ghostty.org/freetype-1220b81f6ecfb3fd222f76cf9106fecfa6554ab0
 https://deps.files.ghostty.org/gettext-0.24.tar.gz
 https://deps.files.ghostty.org/ghostty-themes-release-20260713-155359-c3968b3.tgz
 https://deps.files.ghostty.org/glslang-12201278a1a05c0ce0b6eb6026c65cd3e9247aa041b1c260324bf29cee559dd23ba1.tar.gz
+https://deps.files.ghostty.org/gobject-2026-04-23-26-1.tar.zst
 https://deps.files.ghostty.org/gtk4-layer-shell-1.1.0.tar.gz
 https://deps.files.ghostty.org/harfbuzz-11.0.0.tar.xz
 https://deps.files.ghostty.org/highway-66486a10623fa0d72fe91260f96c892e41aceb06.tar.gz
 https://deps.files.ghostty.org/libpng-1220aa013f0c83da3fb64ea6d327f9173fa008d10e28bc9349eac3463457723b1c66.tar.gz
+https://deps.files.ghostty.org/libxev-9ce8e8e6ff89e583258a7f8e7adeeeaeae8611bf.tar.gz
 https://deps.files.ghostty.org/libxml2-2.11.5.tar.gz
 https://deps.files.ghostty.org/oniguruma-1220c15e72eadd0d9085a8af134904d9a0f5dfcbed5f606ad60edc60ebeccd9706bb.tar.gz
 https://deps.files.ghostty.org/pixels-12207ff340169c7d40c570b4b6a97db614fe47e0d83b5801a932dcd44917424c8806.tar.gz
 https://deps.files.ghostty.org/plasma_wayland_protocols-12207e0851c12acdeee0991e893e0132fc87bb763969a585dc16ecca33e88334c566.tar.gz
 https://deps.files.ghostty.org/sentry-1220446be831adcca918167647c06c7b825849fa3fba5f22da394667974537a9c77e.tar.gz
 https://deps.files.ghostty.org/spirv_cross-1220fb3b5586e8be67bc3feb34cbe749cf42a60d628d2953632c2f8141302748c8da.tar.gz
+https://deps.files.ghostty.org/translate_c-a916baf225a3cfc93a982225462db612604ae290.tar.gz
+https://deps.files.ghostty.org/uucode-2826a37a4562284fdacd8fa029d49509cc9bffcd.tar.gz
+https://deps.files.ghostty.org/vaxis-1dbbe575dff4586fe51e3217aa5c3fecdcbb6089.tar.gz
+https://deps.files.ghostty.org/wayland-0.6.0-lQa1kqz8AQADQmdNJsNhLoNHcnEGEUjrOaPV-dtEnEmX.tar.gz
 https://deps.files.ghostty.org/wayland-9cb3d7aa9dc995ffafdbdef7ab86a949d0fb0e7d.tar.gz
 https://deps.files.ghostty.org/wayland-protocols-258d8f88f2c8c25a830c6316f87d23ce1a0f12d9.tar.gz
 https://deps.files.ghostty.org/wuffs-122037b39d577ec2db3fd7b2130e7b69ef6cc1807d68607a7c232c958315d381b5cd.tar.gz
+https://deps.files.ghostty.org/z2d-0.11.0-j5P_HtLzDwBGyQt49DrT0v4BuVqI_SRs6CXsuj7eBVhR.tar.gz
+https://deps.files.ghostty.org/zf-c35c421f84895193246db06c40683c1a30e616ef.tar.gz
+https://deps.files.ghostty.org/zig_js-3c23860e47fdcdc5af805efb7fd0bdac5fd3e9bc.tar.gz
+https://deps.files.ghostty.org/zig_objc-c8de82ff80281215ad92900866dab7103a8efa8b.tar.gz
 https://deps.files.ghostty.org/zlib-1220fed0c74e1019b3ee29edae2051788b080cd96e90d56836eea857b0b966742efb.tar.gz
-https://github.com/ghostty-org/zig-gobject/releases/download/0.8.0-2026-04-23-26-1/ghostty-gobject-0.8.0-2026-04-23-26-1.tar.zst
-https://github.com/jacobsandlund/uucode/archive/2826a37a4562284fdacd8fa029d49509cc9bffcd.tar.gz
-https://github.com/mitchellh/libxev/archive/9ce8e8e6ff89e583258a7f8e7adeeeaeae8611bf.tar.gz
-https://github.com/mitchellh/zig-js/archive/3c23860e47fdcdc5af805efb7fd0bdac5fd3e9bc.tar.gz
-https://github.com/mitchellh/zig-objc/archive/c8de82ff80281215ad92900866dab7103a8efa8b.tar.gz
-https://github.com/natecraddock/zf/archive/c35c421f84895193246db06c40683c1a30e616ef.tar.gz
-https://github.com/ocornut/imgui/archive/refs/tags/v1.92.5-docking.tar.gz
-https://github.com/rockorager/libvaxis/archive/1dbbe575dff4586fe51e3217aa5c3fecdcbb6089.tar.gz
 https://github.com/vancluever/arocc/archive/ecbc5c799574e0da2758a961b12efa586007f03c.tar.gz
-https://github.com/vancluever/z2d/archive/refs/tags/v0.11.0.tar.gz
-https://gitlab.freedesktop.org/wayland/wayland-protocols/-/archive/1.47/wayland-protocols-1.47.tar.gz
diff --git a/flatpak/zig-packages.json b/flatpak/zig-packages.json
index 01f949fbc..598e64e1a 100644
--- a/flatpak/zig-packages.json
+++ b/flatpak/zig-packages.json
@@ -43,7 +43,7 @@
   },
   {
     "type": "archive",
-    "url": "https://github.com/ghostty-org/zig-gobject/releases/download/0.8.0-2026-04-23-26-1/ghostty-gobject-0.8.0-2026-04-23-26-1.tar.zst",
+    "url": "https://deps.files.ghostty.org/gobject-2026-04-23-26-1.tar.zst",
     "dest": "vendor/p/gobject-0.3.1-Skun7E1KnwBGMX5nslHYG1yWHaSevywxQO8oM7tTOgIp",
     "sha256": "642e324b3644c00464a2161e4af497f73cbbe8ce02a4c0edb92aacb365748047"
   },
@@ -67,7 +67,7 @@
   },
   {
     "type": "archive",
-    "url": "https://github.com/ocornut/imgui/archive/refs/tags/v1.92.5-docking.tar.gz",
+    "url": "https://deps.files.ghostty.org/N-V-__8AAEbOfQBnvcFcCX2W5z7tDaN8vaNZGamEQtNOe0UI.tar.gz",
     "dest": "vendor/p/N-V-__8AAEbOfQBnvcFcCX2W5z7tDaN8vaNZGamEQtNOe0UI",
     "sha256": "c816c20e8c75f3e15ae867350e79925502d1a6a85938bb1a73b8927e5f31f9cb"
   },
@@ -91,7 +91,7 @@
   },
   {
     "type": "archive",
-    "url": "https://github.com/mitchellh/libxev/archive/9ce8e8e6ff89e583258a7f8e7adeeeaeae8611bf.tar.gz",
+    "url": "https://deps.files.ghostty.org/libxev-9ce8e8e6ff89e583258a7f8e7adeeeaeae8611bf.tar.gz",
     "dest": "vendor/p/libxev-0.0.0-86vtcwIRFADbH4hk-EjROXxlrKIRPQdA41XiTSytYO-F",
     "sha256": "e2b9b224cd78101156abb8f46479a51f6cce66c4815c632856e20a1440dd02b7"
   },
@@ -139,13 +139,13 @@
   },
   {
     "type": "archive",
-    "url": "https://codeberg.org/vancluever/translate-c/archive/a916baf225a3cfc93a982225462db612604ae290.tar.gz",
+    "url": "https://deps.files.ghostty.org/translate_c-a916baf225a3cfc93a982225462db612604ae290.tar.gz",
     "dest": "vendor/p/translate_c-0.0.0-Q_BUWj8_BwCr4na219OimiKKj4IVSq0aKtMXCQmIk4AB",
     "sha256": "4fd2a2b21dbc49c22bea6854a59a7568dc77183760531ace3cf8da1267696afd"
   },
   {
     "type": "archive",
-    "url": "https://github.com/jacobsandlund/uucode/archive/2826a37a4562284fdacd8fa029d49509cc9bffcd.tar.gz",
+    "url": "https://deps.files.ghostty.org/uucode-2826a37a4562284fdacd8fa029d49509cc9bffcd.tar.gz",
     "dest": "vendor/p/uucode-0.2.0-ZZjBPlK5VADj7fdoq7G8LIHzD5o6FSkcBXXrRWr4jnrA",
     "sha256": "7e76fc7fab1e7ac728c52b35bbb3e5b8c639841abfc7fe1a4bcb13050594bc9e"
   },
@@ -157,7 +157,7 @@
   },
   {
     "type": "archive",
-    "url": "https://github.com/rockorager/libvaxis/archive/1dbbe575dff4586fe51e3217aa5c3fecdcbb6089.tar.gz",
+    "url": "https://deps.files.ghostty.org/vaxis-1dbbe575dff4586fe51e3217aa5c3fecdcbb6089.tar.gz",
     "dest": "vendor/p/vaxis-0.6.0-BWNV_CrbCQCscGpzsAlR402rYQ_tV3aAl081c2iRRkka",
     "sha256": "3ea050e905887c46bca1a2c18e41d6edf574c1aa6ebfbc5cf3c52846275e4fa8"
   },
@@ -169,15 +169,15 @@
   },
   {
     "type": "archive",
-    "url": "https://deps.files.ghostty.org/wayland-protocols-258d8f88f2c8c25a830c6316f87d23ce1a0f12d9.tar.gz",
-    "dest": "vendor/p/N-V-__8AAKw-DAAaV8bOAAGqA0-oD7o-HNIlPFYKRXSPT03S",
-    "sha256": "5cedcadde81b75e60f23e5e83b5dd2b8eb4efb9f8f79bd7a347d148aeb0530f8"
+    "url": "https://deps.files.ghostty.org/N-V-__8AAFdWDwA0ktbNUi9pFBHCRN4weXIgIfCrVjfGxqgA.tar.gz",
+    "dest": "vendor/p/N-V-__8AAFdWDwA0ktbNUi9pFBHCRN4weXIgIfCrVjfGxqgA",
+    "sha256": "dd2df14ab5f41038257aaedcc4b5fb9ac0ee018f3f0f94af9097028e60d33223"
   },
   {
     "type": "archive",
-    "url": "https://gitlab.freedesktop.org/wayland/wayland-protocols/-/archive/1.47/wayland-protocols-1.47.tar.gz",
-    "dest": "vendor/p/N-V-__8AAFdWDwA0ktbNUi9pFBHCRN4weXIgIfCrVjfGxqgA",
-    "sha256": "dd2df14ab5f41038257aaedcc4b5fb9ac0ee018f3f0f94af9097028e60d33223"
+    "url": "https://deps.files.ghostty.org/wayland-protocols-258d8f88f2c8c25a830c6316f87d23ce1a0f12d9.tar.gz",
+    "dest": "vendor/p/N-V-__8AAKw-DAAaV8bOAAGqA0-oD7o-HNIlPFYKRXSPT03S",
+    "sha256": "5cedcadde81b75e60f23e5e83b5dd2b8eb4efb9f8f79bd7a347d148aeb0530f8"
   },
   {
     "type": "archive",
@@ -187,31 +187,31 @@
   },
   {
     "type": "archive",
-    "url": "https://github.com/vancluever/z2d/archive/refs/tags/v0.11.0.tar.gz",
+    "url": "https://deps.files.ghostty.org/z2d-0.11.0-j5P_HtLzDwBGyQt49DrT0v4BuVqI_SRs6CXsuj7eBVhR.tar.gz",
     "dest": "vendor/p/z2d-0.11.0-j5P_HtLzDwBGyQt49DrT0v4BuVqI_SRs6CXsuj7eBVhR",
     "sha256": "d48b117307f767ca379bf31bd171880e66dcafb89eca4a8f923222619992fcb4"
   },
   {
     "type": "archive",
-    "url": "https://github.com/natecraddock/zf/archive/c35c421f84895193246db06c40683c1a30e616ef.tar.gz",
+    "url": "https://deps.files.ghostty.org/zf-c35c421f84895193246db06c40683c1a30e616ef.tar.gz",
     "dest": "vendor/p/zf-0.11.0-OIRy8X-RAAAwaRXHMYpj2uvBnuGTZWEE_3V7acqHQNtW",
     "sha256": "ca4bc109fd9d97cedae2f5bdb879cc78c346d43c14a34e3a2abd2ee9208c8547"
   },
   {
     "type": "archive",
-    "url": "https://github.com/mitchellh/zig-js/archive/3c23860e47fdcdc5af805efb7fd0bdac5fd3e9bc.tar.gz",
+    "url": "https://deps.files.ghostty.org/zig_js-3c23860e47fdcdc5af805efb7fd0bdac5fd3e9bc.tar.gz",
     "dest": "vendor/p/zig_js-0.0.0-rjCAV7-GAADvMTBL7lPMuvDk7xgS9PCMIZWiOUXLZSlj",
     "sha256": "a2ff488a244301f4e59469a5232aad6869b01acc50f7d7ed2647c029a57d4b3b"
   },
   {
     "type": "archive",
-    "url": "https://github.com/mitchellh/zig-objc/archive/c8de82ff80281215ad92900866dab7103a8efa8b.tar.gz",
+    "url": "https://deps.files.ghostty.org/zig_objc-c8de82ff80281215ad92900866dab7103a8efa8b.tar.gz",
     "dest": "vendor/p/zig_objc-0.0.0-Ir_Sp9gsAQCPAJc0oF5xoWePHWP6Y6tCphDeyNUThJoi",
     "sha256": "831eaec554bb23ef20229f1e705d8f53e8a29c829840bb8d0f5edb05c76d6df0"
   },
   {
     "type": "archive",
-    "url": "https://codeberg.org/ifreund/zig-wayland/archive/v0.6.0.tar.gz",
+    "url": "https://deps.files.ghostty.org/wayland-0.6.0-lQa1kqz8AQADQmdNJsNhLoNHcnEGEUjrOaPV-dtEnEmX.tar.gz",
     "dest": "vendor/p/wayland-0.6.0-lQa1kqz8AQADQmdNJsNhLoNHcnEGEUjrOaPV-dtEnEmX",
     "sha256": "759a632e36a948e0e412d2d74a43a69d2f34e65d40289a16af7aa3725852ef25"
   },
diff --git a/nix/build-support/update-mirror.nu b/nix/build-support/update-mirror.nu
index 8571ddea6..b234172bf 100755
--- a/nix/build-support/update-mirror.nu
+++ b/nix/build-support/update-mirror.nu
@@ -2,23 +2,34 @@
 
 # This script downloads external dependencies from build.zig.zon.json that
 # are not already mirrored at deps.files.ghostty.org, saves them to a local
-# directory, and updates build.zig.zon to point to the new mirror URLs.
+# directory, and updates the build.zig.zon files (the root one as well as
+# every pkg/*/build.zig.zon) to point to the new mirror URLs.
 #
 # The downloaded files are unmodified so their checksums and content hashes
 # will match the originals.
 #
 # After running this script, the files in the output directory can be uploaded
-# to blob storage, and build.zig.zon will already be updated with the new URLs.
+# to blob storage, and the build.zig.zon files will already be updated with
+# the new URLs.
 def main [
   --output: string = "tmp-mirror", # Output directory for the mirrored files
   --prefix: string = "https://deps.files.ghostty.org/", # Final URL prefix to ignore
   --dry-run, # Print what would be downloaded without downloading
 ] {
   let script_dir = ($env.CURRENT_FILE | path dirname)
-  let input_file = ($script_dir | path join ".." ".." "build.zig.zon.json")
-  let zon_file = ($script_dir | path join ".." ".." "build.zig.zon")
+  let root_dir = ($script_dir | path join ".." ".." | path expand)
+  let input_file = ($root_dir | path join "build.zig.zon.json")
   let output_dir = $output
 
+  # All build.zig.zon files that may reference external URLs: the root
+  # one plus every package under pkg/. build.zig.zon.json is generated
+  # from the full dependency tree so it covers all of these.
+  let zon_files = (
+    [($root_dir | path join "build.zig.zon")]
+    | append (glob ($root_dir | path join "pkg" "*" "build.zig.zon"))
+    | sort
+  )
+
   # Ensure the output directory exists
   mkdir $output_dir
 
@@ -75,22 +86,34 @@ def main [
 
   if $dry_run {
     print "Dry run complete - no files were downloaded\n"
-    print $"Would update ($url_replacements | length) URLs in build.zig.zon"
   } else {
     print "All dependencies downloaded successfully\n"
-    print $"Updating ($zon_file)..."
-    
-    # Backup the old file
-    let backup_file = $"($zon_file).bak"
-    cp $zon_file $backup_file
-    print $"Backed up to ($backup_file)"
-    
-    mut zon_content = (open $zon_file)
-    for replacement in $url_replacements {
-      $zon_content = ($zon_content | str replace $replacement.old $replacement.new)
-    }
-    $zon_content | save -f $zon_file
+  }
 
-    print $"Updated ($url_replacements | length) URLs in build.zig.zon"
+  # Apply the URL replacements to every build.zig.zon that references them.
+  for zon_file in $zon_files {
+    mut zon_content = (open --raw $zon_file)
+    mut count = 0
+    for replacement in $url_replacements {
+      if ($zon_content | str contains $replacement.old) {
+        $zon_content = ($zon_content | str replace --all $replacement.old $replacement.new)
+        $count = $count + 1
+      }
+    }
+
+    if $count == 0 {
+      continue
+    }
+
+    let relative_path = ($zon_file | path relative-to $root_dir)
+    if $dry_run {
+      print $"Would update ($count) URLs in ($relative_path)"
+    } else {
+      # Backup the old file
+      let backup_file = $"($zon_file).bak"
+      cp $zon_file $backup_file
+      $zon_content | save -f $zon_file
+      print $"Updated ($count) URLs in ($relative_path), backup at ($relative_path).bak"
+    }
   }
 }
diff --git a/pkg/dcimgui/build.zig.zon b/pkg/dcimgui/build.zig.zon
index 95d0120e1..c488e6122 100644
--- a/pkg/dcimgui/build.zig.zon
+++ b/pkg/dcimgui/build.zig.zon
@@ -15,7 +15,7 @@
 
         .imgui = .{
             // https://github.com/ocornut/imgui
-            .url = "https://github.com/ocornut/imgui/archive/refs/tags/v1.92.5-docking.tar.gz",
+            .url = "https://deps.files.ghostty.org/N-V-__8AAEbOfQBnvcFcCX2W5z7tDaN8vaNZGamEQtNOe0UI.tar.gz",
             .hash = "N-V-__8AAEbOfQBnvcFcCX2W5z7tDaN8vaNZGamEQtNOe0UI",
             .lazy = true,
         },
diff --git a/pkg/gtk4-layer-shell/build.zig.zon b/pkg/gtk4-layer-shell/build.zig.zon
index 042ff96fe..32c7adfc1 100644
--- a/pkg/gtk4-layer-shell/build.zig.zon
+++ b/pkg/gtk4-layer-shell/build.zig.zon
@@ -15,7 +15,7 @@
             .lazy = true,
         },
         .translate_c = .{
-            .url = "https://codeberg.org/vancluever/translate-c/archive/a916baf225a3cfc93a982225462db612604ae290.tar.gz",
+            .url = "https://deps.files.ghostty.org/translate_c-a916baf225a3cfc93a982225462db612604ae290.tar.gz",
             .hash = "translate_c-0.0.0-Q_BUWj8_BwCr4na219OimiKKj4IVSq0aKtMXCQmIk4AB",
             .lazy = true,
         },
diff --git a/pkg/harfbuzz/build.zig.zon b/pkg/harfbuzz/build.zig.zon
index de5ebcf94..c4ee2bdfe 100644
--- a/pkg/harfbuzz/build.zig.zon
+++ b/pkg/harfbuzz/build.zig.zon
@@ -5,7 +5,7 @@
     .paths = .{""},
     .dependencies = .{
         .translate_c = .{
-            .url = "https://codeberg.org/vancluever/translate-c/archive/a916baf225a3cfc93a982225462db612604ae290.tar.gz",
+            .url = "https://deps.files.ghostty.org/translate_c-a916baf225a3cfc93a982225462db612604ae290.tar.gz",
             .hash = "translate_c-0.0.0-Q_BUWj8_BwCr4na219OimiKKj4IVSq0aKtMXCQmIk4AB",
             .lazy = true,
         },
diff --git a/pkg/macos/build.zig.zon b/pkg/macos/build.zig.zon
index 3c2f4448e..58b008c33 100644
--- a/pkg/macos/build.zig.zon
+++ b/pkg/macos/build.zig.zon
@@ -6,7 +6,7 @@
     .dependencies = .{
         .apple_sdk = .{ .path = "../apple-sdk" },
         .translate_c = .{
-            .url = "https://codeberg.org/vancluever/translate-c/archive/a916baf225a3cfc93a982225462db612604ae290.tar.gz",
+            .url = "https://deps.files.ghostty.org/translate_c-a916baf225a3cfc93a982225462db612604ae290.tar.gz",
             .hash = "translate_c-0.0.0-Q_BUWj8_BwCr4na219OimiKKj4IVSq0aKtMXCQmIk4AB",
             .lazy = true,
         },
diff --git a/pkg/wuffs/build.zig.zon b/pkg/wuffs/build.zig.zon
index 338f4f27f..1cf438e8e 100644
--- a/pkg/wuffs/build.zig.zon
+++ b/pkg/wuffs/build.zig.zon
@@ -5,7 +5,7 @@
     .dependencies = .{
         .translate_c = .{
             .lazy = true,
-            .url = "https://codeberg.org/vancluever/translate-c/archive/a916baf225a3cfc93a982225462db612604ae290.tar.gz",
+            .url = "https://deps.files.ghostty.org/translate_c-a916baf225a3cfc93a982225462db612604ae290.tar.gz",
             .hash = "translate_c-0.0.0-Q_BUWj8_BwCr4na219OimiKKj4IVSq0aKtMXCQmIk4AB",
         },
 
diff --git a/src/benchmark/TerminalStream.zig b/src/benchmark/TerminalStream.zig
index 1e5c8aeec..a521c5b7a 100644
--- a/src/benchmark/TerminalStream.zig
+++ b/src/benchmark/TerminalStream.zig
@@ -113,8 +113,10 @@ fn step(ptr: *anyopaque) Benchmark.Error!void {
     // aren't currently IO bound.
     const f = self.data_f orelse return;
 
-    var read_buf: [64 * 1024]u8 align(std.atomic.cache_line) = undefined;
-    var f_reader = f.reader(global.io(), &read_buf);
+    // Unbuffered: readSliceShort below reads directly into `buf`,
+    // avoiding a per-chunk memcpy through an intermediate reader
+    // buffer that would pollute the measurement.
+    var f_reader = f.reader(global.io(), &.{});
     const r = &f_reader.interface;
 
     // This buffer size matches the read buffer size used by the
diff --git a/src/benchmark/cli.zig b/src/benchmark/cli.zig
index 4c31ea8c4..6cab79025 100644
--- a/src/benchmark/cli.zig
+++ b/src/benchmark/cli.zig
@@ -46,7 +46,7 @@ pub const Action = enum {
 
 /// An entrypoint for the benchmark CLI.
 pub fn main(init: std.process.Init) !void {
-    try global.init(.{ .main = init });
+    try global.init(.{ .tool = init });
     const alloc = std.heap.c_allocator;
     const action_ = try cli.action.detectArgs(Action, alloc, init.minimal.args);
     const action = action_ orelse return error.NoAction;
diff --git a/src/build/Config.zig b/src/build/Config.zig
index 20a355cb5..43db20971 100644
--- a/src/build/Config.zig
+++ b/src/build/Config.zig
@@ -669,6 +669,17 @@ pub fn fromOptions() Config {
     };
 }
 
+/// Whether release artifacts should omit frame pointers.
+///
+/// Stripped release builds omit them in general, but we always keep frame
+/// pointers on Apple platforms: the Apple arm64 ABI expects x29 to
+/// be a valid frame pointer and Apple's profiling and crash reporting
+/// tools rely on it for backtraces.
+pub fn omitFramePointer(self: *const Config) bool {
+    if (self.target.result.os.tag.isDarwin()) return false;
+    return self.strip;
+}
+
 /// Returns the minimum OS version for the given OS tag. This shouldn't
 /// be used generally, it should only be used for Darwin-based OS currently.
 pub fn osVersionMin(tag: std.Target.Os.Tag) ?std.Target.Query.OsVersion {
diff --git a/src/build/GhosttyExe.zig b/src/build/GhosttyExe.zig
index 680ac856e..22f39b7b3 100644
--- a/src/build/GhosttyExe.zig
+++ b/src/build/GhosttyExe.zig
@@ -18,7 +18,7 @@ pub fn init(b: *std.Build, cfg: *const Config, deps: *const SharedDeps) !Ghostty
             .target = cfg.target,
             .optimize = cfg.optimize,
             .strip = cfg.strip,
-            .omit_frame_pointer = cfg.strip,
+            .omit_frame_pointer = cfg.omitFramePointer(),
             .unwind_tables = if (cfg.strip) .none else .sync,
         }),
         // Crashes on x86_64 self-hosted on 0.15.1
diff --git a/src/build/GhosttyLib.zig b/src/build/GhosttyLib.zig
index 6fe28370c..529bb2821 100644
--- a/src/build/GhosttyLib.zig
+++ b/src/build/GhosttyLib.zig
@@ -1,9 +1,11 @@
 const GhosttyLib = @This();
 
 const std = @import("std");
+const builtin = @import("builtin");
 const RunStep = std.Build.Step.Run;
 const CombineArchivesStep = @import("CombineArchivesStep.zig");
 const Config = @import("Config.zig");
+const LibsystemOverrideStep = @import("LibsystemOverrideStep.zig");
 const SharedDeps = @import("SharedDeps.zig");
 const LipoStep = @import("LipoStep.zig");
 
@@ -27,7 +29,7 @@ pub fn initStatic(
             .target = deps.config.target,
             .optimize = deps.config.optimize,
             .strip = deps.config.strip,
-            .omit_frame_pointer = deps.config.strip,
+            .omit_frame_pointer = deps.config.omitFramePointer(),
             .unwind_tables = if (deps.config.strip) .none else .sync,
             .link_libc = true,
         }),
@@ -57,9 +59,19 @@ pub fn initStatic(
     const combined = CombineArchivesStep.create(b, deps.config.target, "ghostty-internal", lib_list.items);
     combined.step.dependOn(&lib.step);
 
+    // On Darwin, prefer libSystem's libc/libm over the bundled
+    // compiler-rt for consumers of this archive. See
+    // libsystem_override.sh for details. This is a no-op elsewhere.
+    const override = LibsystemOverrideStep.create(
+        b,
+        deps.config.target,
+        combined.output,
+        "libghostty-internal.a",
+    );
+
     return .{
-        .step = combined.step,
-        .output = combined.output,
+        .step = override.step orelse combined.step,
+        .output = override.output,
 
         // Static libraries cannot have dSYMs because they aren't linked.
         .dsym = null,
@@ -88,7 +100,7 @@ pub fn initShared(
             .target = deps.config.target,
             .optimize = deps.config.optimize,
             .strip = deps.config.strip,
-            .omit_frame_pointer = deps.config.strip,
+            .omit_frame_pointer = deps.config.omitFramePointer(),
             .unwind_tables = if (deps.config.strip) .none else .sync,
         }),
 
diff --git a/src/build/GhosttyLibVt.zig b/src/build/GhosttyLibVt.zig
index 8ff25f503..32ed2aa72 100644
--- a/src/build/GhosttyLibVt.zig
+++ b/src/build/GhosttyLibVt.zig
@@ -5,6 +5,7 @@ const builtin = @import("builtin");
 const assert = std.debug.assert;
 const RunStep = std.Build.Step.Run;
 const CombineArchivesStep = @import("CombineArchivesStep.zig");
+const LibsystemOverrideStep = @import("LibsystemOverrideStep.zig");
 const Config = @import("Config.zig");
 const GhosttyZig = @import("GhosttyZig.zig");
 const LipoStep = @import("LipoStep.zig");
@@ -295,22 +296,44 @@ fn initLib(
         const combined = CombineArchivesStep.create(b, target, "ghostty-vt", sources.items);
         combined.step.dependOn(&lib.step);
 
+        // On Darwin, prefer libSystem's libc/libm over the bundled
+        // compiler-rt for consumers of this archive. See GhosttyLib
+        // and libsystem_override.sh for details.
+        const override = LibsystemOverrideStep.create(
+            b,
+            target,
+            combined.output,
+            "libghostty-vt-fat.a",
+        );
+
         return .{
-            .step = combined.step,
+            .step = override.step orelse combined.step,
             .artifact = &b.addInstallArtifact(lib, .{}).step,
             .kind = kind,
-            .output = combined.output,
+            .output = override.output,
             .dsym = dsymutil,
             .pkg_config = if (pcs) |v| v.shared else null,
             .pkg_config_static = if (pcs) |v| v.static else null,
         };
     }
 
+    // Same libSystem preference for the plain (no vendored SIMD)
+    // static archive; a no-op off Darwin.
+    const override: LibsystemOverrideStep.Result = if (kind == .static) LibsystemOverrideStep.create(
+        b,
+        target,
+        lib.getEmittedBin(),
+        "libghostty-vt-static.a",
+    ) else .{
+        .step = null,
+        .output = lib.getEmittedBin(),
+    };
+
     return .{
-        .step = &lib.step,
+        .step = override.step orelse &lib.step,
         .artifact = &b.addInstallArtifact(lib, .{}).step,
         .kind = kind,
-        .output = lib.getEmittedBin(),
+        .output = override.output,
         .dsym = dsymutil,
         .pkg_config = if (pcs) |v| v.shared else null,
         .pkg_config_static = if (pcs) |v| v.static else null,
diff --git a/src/build/LibsystemOverrideStep.zig b/src/build/LibsystemOverrideStep.zig
new file mode 100644
index 000000000..3e1cafa5e
--- /dev/null
+++ b/src/build/LibsystemOverrideStep.zig
@@ -0,0 +1,51 @@
+//! Wraps a Darwin static archive with the libsystem_override.sh
+//! post-processing step so that consumers linking the archive bind
+//! well-known libc/libm symbols (memcpy, memmove, memset, cos, sin,
+//! ...) to Apple's libSystem instead of the bundled Zig compiler-rt.
+//! See src/build/libsystem_override.sh for the full rationale.
+//!
+//! This applies to every static archive we produce, public
+//! (e.g. libghostty-vt) and app-internal alike: the compiler-rt
+//! bundle must stay because the few symbols libSystem does not
+//! provide (f128 conversions, *q math, sincos*, ___zig_probe_stack)
+//! have live references, e.g. from the bundled ubsan runtime and
+//! x86_64 stack probing in Debug builds.
+//!
+//! Note shared libraries can't use either approach: Zig 0.16 links
+//! compiler-rt as an eagerly-included object, so its definitions are
+//! already bound into the dylib at link time and cannot be repaired
+//! post-hoc. That needs an upstream Zig fix.
+const std = @import("std");
+const builtin = @import("builtin");
+
+pub const Result = struct {
+    /// The step performing the override, or null if the override
+    /// doesn't apply to this target/host (in which case `output` is
+    /// the unmodified input).
+    step: ?*std.Build.Step,
+    output: std.Build.LazyPath,
+};
+
+/// Post-process the given static archive on Darwin. Requires a Darwin
+/// host for the Apple toolchain (nmedit); in all other configurations
+/// this is a no-op and the input is returned unmodified, which is
+/// functional (the bundled compiler-rt symbols are used), just slower.
+pub fn create(
+    b: *std.Build,
+    target: std.Build.ResolvedTarget,
+    input: std.Build.LazyPath,
+    out_name: []const u8,
+) Result {
+    if (!target.result.os.tag.isDarwin() or
+        comptime !builtin.os.tag.isDarwin())
+    {
+        return .{ .step = null, .output = input };
+    }
+
+    const run = b.addSystemCommand(&.{"/bin/sh"});
+    run.setName("libsystem override");
+    run.addFileArg(b.path("src/build/libsystem_override.sh"));
+    run.addFileArg(input);
+    const output = run.addOutputFileArg(out_name);
+    return .{ .step = &run.step, .output = output };
+}
diff --git a/src/build/libsystem_override.sh b/src/build/libsystem_override.sh
new file mode 100755
index 000000000..14ed191b8
--- /dev/null
+++ b/src/build/libsystem_override.sh
@@ -0,0 +1,123 @@
+#!/bin/sh
+#
+# Darwin-only: rewrite a static archive so that consumers linking it bind
+# libc/libm symbols to Apple's libSystem instead of the bundled Zig
+# compiler-rt. This uses the Apple toolchain (xcrun, nmedit) and libSystem
+# semantics, so it must run on a Darwin host for a Darwin target.
+#
+# Background: our static library bundles Zig's compiler-rt, which defines
+# strong global implementations of libc/libm functions (memcpy, memmove,
+# memset, cos, sin, ...). When a consumer (e.g. the macOS app via the
+# XCFramework) links this archive, ld64 resolves those symbols from the
+# archive instead of libSystem, silently replacing Apple's highly
+# optimized implementations (_platform_memmove and friends, vectorized
+# libm) with compiler-rt's generic ones. We measured Zig 0.16 (LLVM 21)
+# compiler-rt memmove costing several percent of PTY throughput on
+# scroll-region workloads versus libSystem's.
+#
+# The mechanism is to localize (make non-external) the libSystem-provided
+# symbols defined by the compiler_rt.o archive member. This keeps
+# compiler_rt.o functional for the intrinsics that libSystem does NOT
+# provide (e.g. the f128 conversions ___extenddftf2/___extendxftf2, *q
+# math, sincos*) while letting every other archive member bind the
+# well-known libc/libm symbols to libSystem at final link.
+#
+# usage: libsystem_override.sh <input.a> <output.a>
+set -eu
+
+in="$1"
+out="$2"
+
+tmp="$(mktemp -d)"
+trap 'rm -rf "$tmp"' EXIT
+
+cp -f "$in" "$out"
+chmod u+w "$out"
+
+# The symbols to prefer from libSystem. Everything listed here is a
+# stable macOS export (verified against libSystem's link surface).
+# Notably NOT listed (not exported by libSystem): the *q (f128)
+# variants, sincos/sincosf/sincosl, and all ___-prefixed compiler
+# intrinsics except the fortify _chk wrappers below.
+cat >"$tmp/localize.txt" <<'EOF'
+_bcmp
+_memcmp
+_memcpy
+_memmove
+_memset
+_strlen
+___memcpy_chk
+___memmove_chk
+___memset_chk
+___strcat_chk
+___strcpy_chk
+_ceil
+_ceilf
+_ceill
+_cos
+_cosf
+_cosl
+_exp
+_exp2
+_exp2f
+_exp2l
+_expf
+_expl
+_fabs
+_fabsf
+_fabsl
+_floor
+_floorf
+_floorl
+_fma
+_fmaf
+_fmal
+_fmax
+_fmaxf
+_fmaxl
+_fmin
+_fminf
+_fminl
+_fmod
+_fmodf
+_fmodl
+_log
+_log10
+_log10f
+_log10l
+_log2
+_log2f
+_log2l
+_logf
+_logl
+_round
+_roundf
+_roundl
+_sin
+_sinf
+_sinl
+_sqrt
+_sqrtf
+_sqrtl
+_tan
+_tanf
+_tanl
+_trunc
+_truncf
+_truncl
+EOF
+
+cd "$tmp"
+
+xcrun ar x "$out" compiler_rt.o
+chmod 644 compiler_rt.o
+
+# nmedit takes a keep-list (-s): all current global definitions except
+# the ones we want to localize.
+xcrun nm -g compiler_rt.o | awk '$2 ~ /^[A-TV-Z]$/ {print $3}' | sort -u >all.txt
+sort -u localize.txt >loc.txt
+comm -23 all.txt loc.txt >keep.txt
+xcrun nmedit -s keep.txt compiler_rt.o
+
+xcrun ar r "$out" compiler_rt.o
+xcrun ranlib "$out" 2>/dev/null || true
diff --git a/src/config/path.zig b/src/config/path.zig
index 5bf0bff39..4d9c8586a 100644
--- a/src/config/path.zig
+++ b/src/config/path.zig
@@ -204,7 +204,7 @@ pub const Path = union(enum) {
         defer dir.close(global.io());
 
         const abs = abs: {
-            const dir_len = dir.realPathFile(global.io(), ".", &buf) catch |err| {
+            const abs_len = dir.realPathFile(global.io(), path, &buf) catch |err| {
                 if (err == error.FileNotFound) {
                     // The file doesn't exist. Try to resolve the relative path
                     // another way.
@@ -229,7 +229,7 @@ pub const Path = union(enum) {
                 return;
             };
 
-            break :abs buf[0..dir_len];
+            break :abs buf[0..abs_len];
         };
 
         log.debug(
diff --git a/src/global.zig b/src/global.zig
index e61f21264..dd9264f3a 100644
--- a/src/global.zig
+++ b/src/global.zig
@@ -35,6 +35,14 @@ var state: ?GlobalState = undefined;
 
 pub const InitOpts = union(enum) {
     main: std.process.Init,
+
+    /// Same as `main` but for auxiliary tool binaries (e.g. ghostty-bench
+    /// and ghostty-gen) that have their own CLI action namespace. This
+    /// skips detection of ghostty app CLI actions, since tool actions
+    /// (e.g. `+terminal-stream`) are not valid app actions and would
+    /// otherwise cause init to fail with InvalidAction.
+    tool: std.process.Init,
+
     c: struct {
         argc: usize,
         argv: [*][*:0]u8,
@@ -52,11 +60,11 @@ pub fn init(opts: InitOpts) !void {
         .gpa = null,
         .alloc = undefined,
         .environ = switch (opts) {
-            .main => |m| m.minimal.environ,
+            .main, .tool => |m| m.minimal.environ,
             .c => |c| c.environ,
         },
         .args = switch (opts) {
-            .main => |m| m.minimal.args,
+            .main, .tool => |m| m.minimal.args,
             // TODO: Using the C API from Windows is unsupported at this time.
             //
             // When do we plan on supporting Windows, it's recommended to
@@ -116,11 +124,16 @@ pub fn init(opts: InitOpts) !void {
     errdefer freeTmpDir(self.alloc, self.tmp_dir_path.?);
 
     // We first try to parse any action that we may be executing.
-    self.action = try cli.action.detectArgs(
-        cli.ghostty.Action,
-        self.alloc,
-        self.args,
-    );
+    // Tool binaries (ghostty-bench, ghostty-gen) have their own action
+    // namespace and detect their own actions, so we skip detection here.
+    self.action = switch (opts) {
+        .main, .c => try cli.action.detectArgs(
+            cli.ghostty.Action,
+            self.alloc,
+            self.args,
+        ),
+        .tool => null,
+    };
 
     // If we have an action executing, we disable logging by default
     // since we write to stderr we don't want logs messing up our
diff --git a/src/lib_vt.zig b/src/lib_vt.zig
index c6ac93743..2475ff786 100644
--- a/src/lib_vt.zig
+++ b/src/lib_vt.zig
@@ -145,6 +145,12 @@ comptime {
     // If we're building the C library (vs. the Zig module) then
     // we want to reference the C API so that it gets exported.
     if (@import("root") == lib) {
+        // Force-reference our memset override so its export is
+        // emitted. This must stay inside the root guard so that
+        // downstream Zig module consumers don't get the override
+        // injected into their binaries. See quirks_memset.zig.
+        _ = @import("quirks_memset.zig");
+
         const c = terminal.c_api;
         @export(&c.key_event_new, .{ .name = "ghostty_key_event_new" });
         @export(&c.key_event_free, .{ .name = "ghostty_key_event_free" });
diff --git a/src/main.zig b/src/main.zig
index a88de728e..fe41640ab 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -21,6 +21,12 @@ pub const std_options: std.Options = if (@hasDecl(entrypoint, "std_options"))
 else
     .{};
 
+comptime {
+    // Force-reference our memset override so its export is emitted.
+    // See quirks_memset.zig for details on why this exists.
+    _ = @import("quirks_memset.zig");
+}
+
 test {
     // Zig 0.16.0 has made test logging more strict. Now, *anything* that gets
     // printed to stderr results in a "failed command" message, even if the
@@ -28,4 +34,5 @@ test {
     // log spam in general), we bump the default testing log level to error.
     std.testing.log_level = std.log.Level.err;
     _ = entrypoint;
+    _ = @import("quirks_memset.zig");
 }
diff --git a/src/main_bench.zig b/src/main_bench.zig
index 9804f51ef..c48724903 100644
--- a/src/main_bench.zig
+++ b/src/main_bench.zig
@@ -1,3 +1,9 @@
 const benchmark = @import("benchmark/main.zig");
 
+comptime {
+    // Force-reference our memset override so its export is emitted.
+    // See quirks_memset.zig for details on why this exists.
+    _ = @import("quirks_memset.zig");
+}
+
 pub const main = benchmark.cli.main;
diff --git a/src/main_c.zig b/src/main_c.zig
index d14a455b4..3e331e022 100644
--- a/src/main_c.zig
+++ b/src/main_c.zig
@@ -44,6 +44,10 @@ comptime {
     // Our benchmark API. We probably want to gate this on a build
     // config in the future but for now we always just export it.
     _ = @import("benchmark/main.zig").CApi;
+
+    // Force-reference our memset override so its export is emitted.
+    // See quirks_memset.zig for details on why this exists.
+    _ = @import("quirks_memset.zig");
 }
 
 /// ghostty_info_s
diff --git a/src/main_gen.zig b/src/main_gen.zig
index 3342bc2e9..d4df3b9ec 100644
--- a/src/main_gen.zig
+++ b/src/main_gen.zig
@@ -1,3 +1,9 @@
 const synthetic = @import("synthetic/main.zig");
 
+comptime {
+    // Force-reference our memset override so its export is emitted.
+    // See quirks_memset.zig for details on why this exists.
+    _ = @import("quirks_memset.zig");
+}
+
 pub const main = synthetic.cli.main;
diff --git a/src/quirks_memset.zig b/src/quirks_memset.zig
new file mode 100644
index 000000000..6293b1c4f
--- /dev/null
+++ b/src/quirks_memset.zig
@@ -0,0 +1,322 @@
+//! Provides a fast `memset` symbol that overrides the slow scalar
+//! implementation provided by Zig 0.16's compiler_rt.
+//!
+//! Consider deleting when upstream ships an optimized compiler_rt
+//! memset (tracked by ziglang/zig#32091, maybe fixed at
+//! ziglang/zig#35754). To verify it is safe to delete, check that
+//! the disassembly of `memset` in a ReleaseFast binary is vectorized
+//! (or at least not a byte-at-a-time loop).
+//!
+//! ## Background
+//!
+//! Zig 0.16.0 globally disabled LLVM loop auto-vectorization to work
+//! around an LLVM 21 miscompilation (llvm/llvm-project#186922, see
+//! the 0.16.0 release notes). compiler_rt's memset is a naive
+//! byte-at-a-time loop that relied entirely on auto-vectorization,
+//! so it now compiles to a scalar loop roughly 24x slower than what
+//! Zig 0.15 produced.
+//!
+//! In benchmarks this made `ghostty-bench +terminal-stream` 2.8x slower on
+//! ASCII input (memset was 63% of all executed instructions!).
+//!
+//! Because compiler_rt's symbol is weak, exporting a strong `memset`
+//! from our own code transparently overrides it everywhere. The
+//! implementation below is manually vectorized with `@Vector`, which
+//! does not depend on the disabled loop vectorizer.
+//!
+//! Other mem functions deliberately not overridden:
+//!
+//! - memcpy/memmove: compiler_rt's implementations are manually
+//!   vectorized upstream ("memcpyFast") and remain fast.
+//! - memcmp/bcmp/strlen: also scalar in 0.16, but they never showed
+//!   up in our profiles.
+//!
+//! This file has no effect unless it is referenced from an artifact
+//! root (e.g. `comptime { _ = @import("quirks_memset.zig"); }`).
+//! It must NOT be imported from shared code, otherwise downstream
+//! consumers of our Zig modules would get this export injected into
+//! their binaries.
+//!
+//! ## References
+//!
+//! I referenced the musl asm + c memset implementation (MIT licensed).
+//! The primary thing I took away from that is the dc zva trick for
+//! aarch64. The remainder is fairly obvious memset work.
+
+const std = @import("std");
+const builtin = @import("builtin");
+
+comptime {
+    // Strong linkage when we control the final link (executables,
+    // shared libraries), weak otherwise.
+    const linkage: std.builtin.GlobalLinkage = switch (builtin.output_mode) {
+        .Exe => .strong,
+        .Lib => switch (builtin.link_mode) {
+            .dynamic => .strong,
+            .static => .weak,
+        },
+        .Obj => .weak,
+    };
+
+    // Whether the override is emitted:
+    //
+    //   1. On targets without SIMD we disable, since compiler_rt's
+    //      scalar operations are going to be just as good.
+    //   2. The C object format target uses strong linkage which
+    //      conflits with ours and errors.
+    //   3. Weak COFF builds fatally error because MSVC's linker
+    //      errors when two identical linked symbols exist. MSVC has
+    //      CRT which links so we don't need this there anyways.
+    const enabled =
+        std.simd.suggestVectorLength(u8) != null and
+        builtin.object_format != .c and
+        !(linkage == .weak and builtin.object_format == .coff);
+
+    if (enabled) @export(&memset, .{
+        .name = "memset",
+        .linkage = linkage,
+
+        // Hidden so that shared library builds (libghostty,
+        // libghostty-vt) resolve this internally without exporting
+        // it to their host applications.
+        .visibility = .hidden,
+    });
+}
+
+/// Bytes stored per loop iteration. Twice the native vector size so
+/// each iteration issues two vector stores (e.g. `stp q0, q0` on
+/// aarch64). Capped at 128 both because the small path below relies
+/// on len < 128 once the loop is skipped, and because wider single
+/// iterations stop paying off anyway (e.g. on scalable-vector
+/// targets that suggest very large lengths).
+const vec_bytes = @min(128, 2 * (std.simd.suggestVectorLength(u8) orelse 8));
+
+/// Whether the `dc zva` fast path for large zero fills is available.
+/// `dc zva` zeroes a whole cacheline per instruction without moving data
+/// through the store pipeline. Based on musl.
+const zva_enabled = builtin.cpu.arch == .aarch64 and
+    builtin.os.tag != .freestanding;
+
+/// Only use `dc zva` at or above this many bytes. Below this our
+/// plain vector loop measures faster. Empirically mesaured.
+const zva_threshold = 16384;
+
+/// Matches compiler_rt's memset signature (lib/compiler_rt.zig).
+fn memset(dest: ?[*]u8, c: u8, len: usize) callconv(.c) ?[*]u8 {
+    @setRuntimeSafety(false);
+
+    if (len == 0) return dest;
+    const d = dest.?;
+
+    // Large path: full-width vector stores.
+    if (len >= vec_bytes) {
+        // Very large zero fills: zero whole cachelines with `dc zva`
+        // instead. Only implemented for the (universal in practice)
+        // 64-byte block size; anything else falls through to the
+        // vector loop.
+        if (comptime zva_enabled) {
+            if (len >= zva_threshold and c == 0) zva: {
+                if (zvaSize() != 64) break :zva;
+                const splat64: @Vector(64, u8) = @splat(0);
+
+                // Head: one unaligned store covering every byte up
+                // to the first 64-aligned address (and usually a bit
+                // beyond it; the overlap is fine).
+                const addr = @intFromPtr(d);
+                const aligned = std.mem.alignForward(usize, addr, 64);
+                d[0..64].* = splat64;
+
+                // Zero whole aligned cachelines while at least one
+                // full line remains in range. `dc zva` requires the
+                // WHOLE line to be inside the buffer: it always
+                // zeroes all 64 bytes.
+                var p: [*]u8 = @ptrFromInt(aligned);
+                const end_addr = addr + len;
+                while (@intFromPtr(p) + 64 <= end_addr) : (p += 64) {
+                    asm volatile ("dc zva, %[ptr]"
+                        :
+                        : [ptr] "r" (p),
+                        : .{ .memory = true });
+                }
+
+                // Tail: overlapping unaligned store anchored to the
+                // end of the buffer, covering whatever the line loop
+                // could not. len >= zva_threshold >= 64 so this
+                // cannot underflow.
+                d[len - 64 ..][0..64].* = splat64;
+                return dest;
+            }
+        }
+
+        const splat: @Vector(vec_bytes, u8) = @splat(c);
+
+        // Fill [0, N) where N is len rounded down to a multiple of
+        // vec_bytes.
+        var i: usize = 0;
+        while (i + vec_bytes <= len) : (i += vec_bytes) {
+            d[i..][0..vec_bytes].* = splat;
+
+            // This empty asm statement prevents LLVM's
+            // LoopIdiomRecognize pass from replacing this loop with
+            // a call to memset, which would be infinite recursion
+            // since we ARE memset. compiler_rt is protected from
+            // this by being built with -fno-builtin; Ghostty is not.
+            asm volatile ("" ::: .{ .memory = true });
+        }
+
+        // Fill the remaining [N, len) tail, if any, with one more
+        // full-width store anchored to the END of the buffer. It
+        // overlaps up to vec_bytes-1 bytes that the loop already
+        // wrote, which is fine (same value), and cannot underflow
+        // because len >= vec_bytes in this path.
+        if (i != len) d[len - vec_bytes ..][0..vec_bytes].* = splat;
+        return dest;
+    }
+
+    // Small path (len < vec_bytes): pairs of narrower stores, one
+    // anchored to the start of the buffer and one to the end.
+    //
+    // The invariant for each branch below: a store of width w at
+    // [0..w] plus a store at [len-w..len] covers every byte exactly
+    // when w <= len <= 2*w. Smaller lens are handled by a later
+    // branch; larger lens by an earlier one.
+
+    comptime std.debug.assert(vec_bytes <= 128);
+    if (comptime vec_bytes > 64) {
+        if (len >= 64) {
+            // 64 <= len < vec_bytes <= 128 (asserted above): one
+            // pair of 64-byte stores covers len <= 128. Only emitted
+            // when vec_bytes > 64 (e.g. AVX-512), otherwise the
+            // vector loop above already handled these lengths.
+            const splat64: @Vector(64, u8) = @splat(c);
+            d[0..64].* = splat64;
+            d[len - 64 ..][0..64].* = splat64;
+            return dest;
+        }
+    }
+    if (len >= 16) {
+        // 16 <= len < @min(vec_bytes, 64), so at most 63. One pair
+        // of 16-byte stores covers len <= 32. For 32 < len < 64, a
+        // second pair extends the covered prefix to [0..32] and the
+        // covered suffix to [len-32..len], which meet or overlap in
+        // the middle.
+        const splat16: @Vector(16, u8) = @splat(c);
+        d[0..16].* = splat16;
+        d[len - 16 ..][0..16].* = splat16;
+        if (len > 32) {
+            d[16..32].* = splat16;
+            d[len - 32 ..][0..16].* = splat16;
+        }
+        return dest;
+    }
+    if (len >= 8) {
+        // 8 <= len <= 15: one 8-byte pair (covers len <= 16).
+        const splat8: @Vector(8, u8) = @splat(c);
+        d[0..8].* = splat8;
+        d[len - 8 ..][0..8].* = splat8;
+        return dest;
+    }
+    if (len >= 4) {
+        // 4 <= len <= 7: one 4-byte pair (covers len <= 8).
+        const splat4: @Vector(4, u8) = @splat(c);
+        d[0..4].* = splat4;
+        d[len - 4 ..][0..4].* = splat4;
+        return dest;
+    }
+
+    // 1 <= len <= 3: too short for the pair trick; write bytes one
+    // at a time. The asm statement again keeps LoopIdiomRecognize
+    // from turning this into a recursive memset call; LLVM will do
+    // that even for a loop this short because the trip count is not
+    // statically known.
+    var i: usize = 0;
+    while (i < len) : (i += 1) {
+        d[i] = c;
+        asm volatile ("" ::: .{ .memory = true });
+    }
+    return dest;
+}
+
+/// Cached `dc zva` block size: 0 = not yet queried, 1 = unavailable
+/// or prohibited, otherwise the block size in bytes. Racing threads
+/// store the same value so the memory ordering is irrelevant.
+var zva_size: std.atomic.Value(usize) = .init(0);
+
+fn zvaSize() usize {
+    const cached = zva_size.load(.monotonic);
+    if (cached != 0) return cached;
+    const dczid = asm ("mrs %[out], dczid_el0"
+        : [out] "=r" (-> u64),
+    );
+    // Bit 4 (DZP) prohibits DC ZVA; bits 0-3 are log2 of the block
+    // size in 4-byte words.
+    const size: usize = if (dczid & 0x10 != 0)
+        1
+    else
+        @as(usize, 4) << @intCast(dczid & 0xF);
+    zva_size.store(size, .monotonic);
+    return size;
+}
+
+test memset {
+    const testing = std.testing;
+
+    // A buffer larger than anything the small/vector paths special
+    // case, with room for offset (alignment) variations. Guard bytes
+    // around the fill region must remain untouched.
+    var buf: [4 * vec_bytes + 33]u8 = undefined;
+    for (0..vec_bytes + 1) |offset| {
+        for (0..buf.len - offset) |len| {
+            for ([_]u8{ 0x00, 0x5C, 0xFF }) |c| {
+                @memset(&buf, 0xAA);
+                const region = buf[offset..][0..len];
+                const ret = memset(region.ptr, c, len);
+                try testing.expectEqual(region.ptr, ret.?);
+                for (buf[0..offset]) |b| try testing.expectEqual(0xAA, b);
+                for (region) |b| try testing.expectEqual(c, b);
+                for (buf[offset + len ..]) |b| try testing.expectEqual(0xAA, b);
+            }
+        }
+    }
+
+    // Zero length must not touch memory and must tolerate null.
+    try testing.expectEqual(null, memset(null, 0x11, 0));
+    var one: [1]u8 = .{0xAA};
+    _ = memset(&one, 0x11, 0);
+    try testing.expectEqual(0xAA, one[0]);
+}
+
+test "memset large zero fills (dc zva path)" {
+    const testing = std.testing;
+    const alloc = testing.allocator;
+
+    // Sizes at and around the ZVA threshold, with a guard byte on
+    // each side and every offset within a cacheline so the head and
+    // tail alignment handling is fully exercised.
+    const buf = try alloc.alloc(u8, 2 * zva_threshold + 66);
+    defer alloc.free(buf);
+
+    for ([_]usize{
+        zva_threshold - 1,
+        zva_threshold,
+        zva_threshold + 63,
+        2 * zva_threshold,
+    }) |len| {
+        for (0..65) |offset| {
+            @memset(buf, 0xAA);
+            const region = buf[1 + offset ..][0..len];
+            _ = memset(region.ptr, 0x00, len);
+            for (buf[0 .. 1 + offset]) |b| try testing.expectEqual(0xAA, b);
+            for (region) |b| try testing.expectEqual(0x00, b);
+            for (buf[1 + offset + len ..]) |b| try testing.expectEqual(0xAA, b);
+        }
+    }
+
+    // Nonzero fills of ZVA-eligible sizes must not take the ZVA path
+    // (it can only write zeroes).
+    @memset(buf, 0xAA);
+    _ = memset(buf.ptr + 1, 0x5C, zva_threshold);
+    try testing.expectEqual(0xAA, buf[0]);
+    for (buf[1 .. 1 + zva_threshold]) |b| try testing.expectEqual(0x5C, b);
+    try testing.expectEqual(0xAA, buf[1 + zva_threshold]);
+}
diff --git a/src/simd/main.zig b/src/simd/main.zig
index aabdd21d1..8a3f00670 100644
--- a/src/simd/main.zig
+++ b/src/simd/main.zig
@@ -9,6 +9,18 @@ pub const index_of = @import("index_of.zig");
 pub const vt = @import("vt.zig");
 pub const codepointWidth = codepoint_width.codepointWidth;
 
+/// The number of vector lanes to use for manually vectorized hot
+/// loops operating on elements of type T, or null if the target has
+/// no usable SIMD support and a plain scalar loop should be used
+/// instead (e.g. wasm32 without simd128).
+///
+/// This is twice the native vector width so that each iteration works
+/// two vector registers, giving better instruction-level parallelism.
+pub fn lanes(comptime T: type) ?comptime_int {
+    const native = std.simd.suggestVectorLength(T) orelse return null;
+    return native * 2;
+}
+
 test {
     @import("std").testing.refAllDecls(@This());
 }
diff --git a/src/synthetic/cli.zig b/src/synthetic/cli.zig
index 12acfaa1f..dcac0d0dc 100644
--- a/src/synthetic/cli.zig
+++ b/src/synthetic/cli.zig
@@ -1,7 +1,6 @@
 const std = @import("std");
 const Allocator = std.mem.Allocator;
 const cli = @import("../cli.zig");
-const global = @import("../global.zig");
 
 /// The available actions for the CLI. This is the list of available
 /// synthetic generators. View docs for each individual one in the
@@ -93,7 +92,7 @@ fn mainActionImpl(
 
     // Our output always goes to stdout.
     var buffer: [2048]u8 = undefined;
-    var stdout_writer = std.Io.File.stdout().writer(global.io(), &buffer);
+    var stdout_writer = std.Io.File.stdout().writer(io, &buffer);
     const writer = &stdout_writer.interface;
 
     // Create our implementation
diff --git a/src/terminal/Terminal.zig b/src/terminal/Terminal.zig
index 98a64ef83..6ec768f4f 100644
--- a/src/terminal/Terminal.zig
+++ b/src/terminal/Terminal.zig
@@ -10,6 +10,7 @@ const assert = @import("../quirks.zig").inlineAssert;
 const tripwire = @import("../tripwire.zig");
 const testing = std.testing;
 const Allocator = std.mem.Allocator;
+const simd = @import("../simd/main.zig");
 const unicode = @import("../unicode/main.zig");
 const uucode = @import("uucode");
 
@@ -630,6 +631,85 @@ inline fn printSliceEligible(cp: u32, comptime width: PrintSliceWidth) bool {
     });
 }
 
+/// Store a run of narrow codepoint cells built from a bit template:
+/// for each `idx` in `[from, to)`, `cells[idx]` is assigned the bits
+/// `template_bits | (cps[idx] << cp_shift)`.
+///
+/// The template is a complete Cell (content tag, style, wide state,
+/// etc. already baked in by the caller) whose codepoint content bits
+/// are zero. Since Cell is a packed struct(u64), OR-ing a codepoint
+/// into the content field's bit position yields a finished cell as a
+/// single integer, keeping the loop pure data movement: no per-cell
+/// field assignments and no branches.
+///
+/// This loop is manually vectorized: Zig 0.16 (LLVM 21) no longer
+/// auto-vectorizes the scalar form the way Zig 0.15 (LLVM 20) did.
+inline fn printSliceStoreRun(
+    cells: [*]Cell,
+    cps: [*]const u32,
+    from: usize,
+    to: usize,
+    template_bits: u64,
+) void {
+    // The bit position of the `content` field within the packed
+    // Cell. A codepoint occupies the low bits of `content`, so
+    // shifting a codepoint left by this amount places it exactly
+    // where `.content = .{ .codepoint = .{ .data = cp } }` would.
+    const cp_shift = @bitOffsetOf(Cell, "content");
+
+    // Since codepoints are OR'd into the content field rather than
+    // assigned, any nonzero content bits in the template would
+    // corrupt the stored codepoints.
+    const content_mask: u64 = comptime mask: {
+        const bits = @bitSizeOf(@FieldType(Cell, "content"));
+        break :mask ((1 << bits) - 1) << cp_shift;
+    };
+    assert(template_bits & content_mask == 0);
+
+    var idx = from;
+
+    // Vectorized bulk of the run.
+    if (simd.lanes(u64)) |lanes| {
+        // u64 due to backing integer of Cell
+        const V = @Vector(lanes, u64);
+
+        // The template and shift amount are loop-invariant, so
+        // broadcast them to every lane once up front.
+        const template: V = @splat(template_bits);
+        const shift: @Vector(
+            lanes,
+            std.math.Log2Int(u64),
+        ) = @splat(cp_shift);
+
+        while (idx + lanes <= to) : (idx += lanes) {
+            // Load `lanes` decoded codepoints...
+            const narrow: @Vector(lanes, u32) = cps[idx..][0..lanes].*;
+
+            // ...widen each u32 lane to the u64 cell size...
+            const wide: V = @intCast(narrow);
+
+            // ...shift each codepoint into the content field's bit
+            // position and merge with the template, producing
+            // `lanes` finished cells (coerced from vector to array
+            // so they can be bitcast for the store below)...
+            const bits: [lanes]u64 = template | (wide << shift);
+
+            // ...and store them contiguously. Cell is a packed
+            // struct(u64) so an array of u64 bit patterns has
+            // identical layout to an array of cells.
+            cells[idx..][0..lanes].* = @bitCast(bits);
+        }
+    }
+
+    // Scalar tail: the final `< lanes` cells of the run, or the
+    // entire run on targets without SIMD. Note `idx` carries over
+    // from the vector loop above. This is the same computation as
+    // the vector body, one cell at a time.
+    while (idx < to) : (idx += 1) {
+        cells[idx] = @bitCast(template_bits | (@as(u64, cps[idx]) << cp_shift));
+    }
+}
+
 /// The row-filling portion of the printSlice fast path, specialized by
 /// width class. The first codepoint must already be validated by the
 /// caller (printSliceFast).
@@ -671,19 +751,20 @@ fn printSliceFill(
         // Anything else (including eligible unicode) proceeds via
         // the scalar loop below.
         if (comptime width == .narrow) {
-            const lanes = 8;
-            const V = @Vector(lanes, u32);
-            const lo: V = @splat(0x10);
-            const hi: V = @splat(0xFF);
-            while (idx + lanes <= cps.len) {
-                const v: V = cps[idx..][0..lanes].*;
-                const in_range = (v >= lo) & (v <= hi);
-                if (!@reduce(.And, in_range)) {
-                    const bits: std.meta.Int(.unsigned, lanes) = @bitCast(in_range);
-                    idx += @ctz(~bits);
-                    break;
+            if (simd.lanes(u32)) |lanes| {
+                const V = @Vector(lanes, u32);
+                const lo: V = @splat(0x10);
+                const hi: V = @splat(0xFF);
+                while (idx + lanes <= cps.len) {
+                    const v: V = cps[idx..][0..lanes].*;
+                    const in_range = (v >= lo) & (v <= hi);
+                    if (!@reduce(.And, in_range)) {
+                        const bits: std.meta.Int(.unsigned, lanes) = @bitCast(in_range);
+                        idx += @ctz(~bits);
+                        break;
+                    }
+                    idx += lanes;
                 }
-                idx += lanes;
             }
         }
 
@@ -817,12 +898,38 @@ fn printSliceFill(
                 // We can only write whole (wide, spacer) pairs.
                 const pair_end = k + (simple - k) / 2 * 2;
                 var idx = k;
+
+                // Manually vectorized for the same reason as
+                // printSliceStoreRun: build a vector of wide cells,
+                // interleave with spacer tails, and store (wide,
+                // spacer) pairs several at a time.
+                if (simd.lanes(u64)) |lanes| {
+                    const pair_lanes = lanes / 2;
+                    const Vp = @Vector(pair_lanes, u64);
+                    const wide_v: Vp = @splat(wide_bits);
+                    const spacer_v: Vp = @splat(spacer_bits);
+                    const shift_v: @Vector(
+                        pair_lanes,
+                        std.math.Log2Int(u64),
+                    ) = @splat(cp_shift);
+                    while (idx + 2 * pair_lanes <= pair_end) : (idx += 2 * pair_lanes) {
+                        const narrow: @Vector(pair_lanes, u32) =
+                            cps[printed + idx / 2 ..][0..pair_lanes].*;
+                        const wides: Vp = wide_v | (@as(Vp, @intCast(narrow)) << shift_v);
+                        const inter: [2 * pair_lanes]u64 = std.simd.interlace(.{
+                            wides,
+                            spacer_v,
+                        });
+                        cells[idx..][0 .. 2 * pair_lanes].* = @bitCast(inter);
+                    }
+                }
                 while (idx < pair_end) : (idx += 2) {
                     cells[idx] = @bitCast(
                         wide_bits | (@as(u64, cps[printed + idx / 2]) << cp_shift),
                     );
                     cells[idx + 1] = @bitCast(spacer_bits);
                 }
+
                 // If the simple run ended mid-pair we stop at the pair
                 // boundary and handle the offending cell below.
                 k = pair_end;
@@ -832,11 +939,13 @@ fn printSliceFill(
                     simple = pair_end;
                 }
             } else {
-                for (k..simple) |idx| {
-                    cells[idx] = @bitCast(
-                        template_bits | (@as(u64, cps[printed + idx]) << cp_shift),
-                    );
-                }
+                printSliceStoreRun(
+                    cells,
+                    cps.ptr + printed,
+                    k,
+                    simple,
+                    template_bits,
+                );
                 k = simple;
             }
             if (k >= cell_count) break;
@@ -888,11 +997,13 @@ fn printSliceFill(
                     page.styles.useMultiple(page.memory, style_id, @intCast(n));
                 }
 
-                for (k..m) |idx| {
-                    cells[idx] = @bitCast(
-                        template_bits | (@as(u64, cps[printed + idx]) << cp_shift),
-                    );
-                }
+                printSliceStoreRun(
+                    cells,
+                    cps.ptr + printed,
+                    k,
+                    m,
+                    template_bits,
+                );
                 k = m;
                 continue :fill;
             }
diff --git a/src/terminal/hash_map.zig b/src/terminal/hash_map.zig
index d8feddcd1..abef87e3b 100644
--- a/src/terminal/hash_map.zig
+++ b/src/terminal/hash_map.zig
@@ -70,8 +70,24 @@ fn AutoHashMapUnmanaged(
 
 fn AutoContext(comptime K: type) type {
     return struct {
-        pub const hash = std.hash_map.getAutoHashFn(K, @This());
         pub const eql = std.hash_map.getAutoEqlFn(K, @This());
+
+        pub fn hash(_: @This(), key: K) u64 {
+            if (comptime std.meta.hasUniqueRepresentation(K)) {
+                // LLVM 21 (Zig 0.16) failed to inline this which resulted
+                // in a measurable almost 2x slowdown on our hyperlink map
+                // benchmark. So, force it.
+                return @call(
+                    .always_inline,
+                    std.hash.Wyhash.hash,
+                    .{ 0, std.mem.asBytes(&key) },
+                );
+            }
+
+            var hasher = std.hash.Wyhash.init(0);
+            std.hash.autoHash(&hasher, key);
+            return hasher.final();
+        }
     };
 }
 
diff --git a/src/terminal/stream.zig b/src/terminal/stream.zig
index 31769df03..791d0c55d 100644
--- a/src/terminal/stream.zig
+++ b/src/terminal/stream.zig
@@ -579,8 +579,30 @@ pub fn Stream(comptime H: type) type {
                         continue;
                     }
 
+                    // Find the end of the printable run. This is an
+                    // early-exit search loop that LLVM won't
+                    // auto-vectorize, and printable runs dominate real
+                    // input, so scan several codepoints at a time
+                    // manually (same idiom as the printSliceFill run
+                    // scan).
                     var end = i + 1;
-                    while (end < cps.len and cps[end] > 0xF) end += 1;
+                    scan: {
+                        if (simd.lanes(u32)) |lanes| {
+                            const V = @Vector(lanes, u32);
+                            const threshold: V = @splat(0xF);
+                            while (end + lanes <= cps.len) {
+                                const v: V = cps[end..][0..lanes].*;
+                                const gt = v > threshold;
+                                if (!@reduce(.And, gt)) {
+                                    const bits: std.meta.Int(.unsigned, lanes) = @bitCast(gt);
+                                    end += @ctz(~bits);
+                                    break :scan;
+                                }
+                                end += lanes;
+                            }
+                        }
+                        while (end < cps.len and cps[end] > 0xF) end += 1;
+                    }
                     self.handler.vt(.print_slice, .{ .cps = cps[i..end] });
                     i = end;
                 }
diff --git a/src/unicode/grapheme.zig b/src/unicode/grapheme.zig
index eed5e6e75..799689357 100644
--- a/src/unicode/grapheme.zig
+++ b/src/unicode/grapheme.zig
@@ -141,8 +141,8 @@ inline fn invalidCodepoint(cp: anytype) bool {
 
 /// This is all the structures and data for the precomputed lookup table
 /// for all possible permutations of state and grapheme break properties.
-/// Precomputation requires 2^13 keys of 4 bit values so the whole table is
-/// 8KB.
+/// Precomputation requires 2^13 keys of byte-sized values so the whole
+/// table is 8KB.
 const Precompute = struct {
     const Key = packed struct(u13) {
         state: uucode.grapheme.BreakState,
@@ -154,9 +154,15 @@ const Precompute = struct {
         }
     };
 
-    const Value = packed struct(u4) {
+    const Value = packed struct(u8) {
         result: bool,
         state: uucode.grapheme.BreakState,
+
+        /// Explicit padding to give the struct a power-of-two backing
+        /// integer, for the same reason as `Properties._padding` (avoids
+        /// exotic-width LLVM integer accesses that defeat register
+        /// promotion). @sizeOf was already 1, so the table stays 8KB.
+        _padding: u4 = 0,
     };
 
     const data = precompute: {
diff --git a/src/unicode/props.zig b/src/unicode/props.zig
index 6a4169747..dd6a4dbb1 100644
--- a/src/unicode/props.zig
+++ b/src/unicode/props.zig
@@ -7,7 +7,7 @@
 const std = @import("std");
 const uucode = @import("uucode");
 
-pub const Properties = packed struct {
+pub const Properties = packed struct(u16) {
     /// Codepoint width. We clamp to [0, 2] since Ghostty handles control
     /// characters and we max out at 2 for wide characters (i.e. 3-em dash
     /// becomes a 2-em dash).
@@ -23,6 +23,16 @@ pub const Properties = packed struct {
     /// Emoji VS compatibility
     emoji_vs_base: bool = false,
 
+    /// Explicit padding to give the struct a power-of-two backing integer.
+    /// This is a performance workaround: with a non-power-of-two backing
+    /// integer (u9), Zig 0.16 lowers loads/stores of this struct through
+    /// mismatched exotic-width LLVM integer types (store i9 / load i16),
+    /// which blocks LLVM from promoting temporaries to registers and forces
+    /// stack round-trips in hot paths like `graphemeBreak`. See
+    /// https://github.com/ziglang/zig/issues/21891 for the upstream issue.
+    /// The size of the lookup table is unchanged (@sizeOf was already 2).
+    _padding: u7 = 0,
+
     // Needed for lut.Generator
     pub fn eql(a: Properties, b: Properties) bool {
         return a.width == b.width and