From 931a538a3992c0f33c6647360bd15ff54f0f7a87 Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <m@mitchellh.com>
Date: Sun, 9 Aug 2026 20:22:28 -0700
Subject: [PATCH] comments

---
 src/App.zig            | 17 ++---------------
 src/renderer/Metal.zig |  6 ------
 2 files changed, 2 insertions(+), 21 deletions(-)

diff --git a/src/App.zig b/src/App.zig
index 15e06a03a..28bbd83f1 100644
--- a/src/App.zig
+++ b/src/App.zig
@@ -79,21 +79,6 @@ pub fn create(alloc: Allocator) CreateError!*App {
     errdefer alloc.destroy(app);
     try app.init(alloc);
 
-    // Warm up system services on background threads. These are
-    // multi-millisecond one-time costs that would otherwise be paid
-    // during the first surface's initialization. Doing it here overlaps
-    // them with the rest of app startup (config, app runtime, window
-    // creation).
-    threadedWarmup();
-
-    return app;
-}
-
-/// Warm up system services whose first use in a process is slow. Each
-/// subsystem gets its own background thread so that one slow subsystem
-/// doesn't delay the others. Only operations that are safe to run on
-/// any thread belong here.
-fn threadedWarmup() void {
     // If font discovery supports warmup, then we call it. Some font
     // mechanisms (e.g. CoreText) have a multi-millisecond one-time cost
     // on startup.
@@ -118,6 +103,8 @@ fn threadedWarmup() void {
             log.warn("renderer warmup thread spawn failed err={}", .{err});
         }
     }
+
+    return app;
 }
 
 /// Initialize the main app instance. This creates the main window, sets
diff --git a/src/renderer/Metal.zig b/src/renderer/Metal.zig
index 7b59ce500..9247454db 100644
--- a/src/renderer/Metal.zig
+++ b/src/renderer/Metal.zig
@@ -413,12 +413,6 @@ pub inline fn beginFrame(
 /// thread at app startup; Metal device queries are thread-safe) moves
 /// that one-time cost off the critical path of the first surface's
 /// renderer initialization.
-///
-/// We deliberately do NOT cache the chosen device: the device set can
-/// change at runtime (e.g. an eGPU being plugged in or removed) and
-/// chooseDevice prefers removable GPUs, so every renderer init must
-/// re-choose. Only the underlying framework initialization is a
-/// one-time cost.
 pub fn warmup() void {
     const device = chooseDevice() catch return;
     defer device.release();