perf: Improve startup performance, b=no-bug, c=common

.github/workflows/build.yml

@@ -336,7 +336,7 @@ jobs:
       MOZ_BUILD_DATE: ${{needs.buildid.outputs.buildids}}
       use-sccache: ${{ inputs.use-sccache }}
 
-  mac-pgo-generate:
+  mac:
     name: macOS build
     uses: ./.github/workflows/macos-release-build.yml
     permissions:
@@ -348,21 +348,6 @@ jobs:
       release-branch: ${{ inputs.update_branch }}
       MOZ_BUILD_DATE: ${{needs.buildid.outputs.buildids}}
       use-sccache: ${{ inputs.use-sccache }}
-      generate-pgo-data: true
-
-  mac:
-    name: macOS build
-    uses: ./.github/workflows/macos-release-build.yml
-    permissions:
-      contents: write
-    secrets: inherit
-    needs: [build-data, buildid, mac-pgo-generate]
-    with:
-      build-version: ${{ needs.build-data.outputs.version }}
-      release-branch: ${{ inputs.update_branch }}
-      MOZ_BUILD_DATE: ${{needs.buildid.outputs.buildids}}
-      use-sccache: ${{ inputs.use-sccache }}
-      generate-pgo-data: false
 
   mac-uni:
     name: macOS build (Universal)

.github/workflows/macos-release-build.yml

@@ -22,11 +22,6 @@ on:
         required: true
         type: boolean
         default: false
-      generate-pgo-data:
-        description: 'Generate PGO data'
-        required: false
-        type: boolean
-        default: false
 
 jobs:
   mac-build:
@@ -73,8 +68,8 @@ jobs:
 
       - name: Setup Git
         run: |
-          git config --global user.email "mr-cheffy@users.noreply.github.com"
-          git config --global user.name "mr-cheffy"
+          git config --global user.email "mauro-balades@users.noreply.github.com"
+          git config --global user.name "mauro-balades"
 
       - name: Install system dependencies
         run: |
@@ -125,20 +120,6 @@ jobs:
           SURFER_COMPAT: ${{ matrix.arch }}
         run: npm run import -- --verbose
 
-      - name: Download PGO data
-        if: ${{ inputs.generate-pgo-data == false }}
-        uses: actions/download-artifact@v4
-        with:
-          name: zen-macos-pgo-data-${{ matrix.arch }}
-
-      - name: Move PGO data
-        if: ${{ inputs.generate-pgo-data == false }}
-        run: |
-          mkdir -p $(echo ~)/artifact
-          mv $GITHUB_WORKSPACE/zen-macos-pgo-data-${{ matrix.arch }}/* $(echo ~)/artifact
-          chmod +x ~/artifact/en-US.log
-          chmod +x ~/artifact/merged.profdata
-
       - name: Bootstrap
         run: |
           cd engine
@@ -161,7 +142,6 @@ jobs:
         env:
           SURFER_COMPAT: ${{ matrix.arch }}
           ZEN_RELEASE_BRANCH: ${{ inputs.release-branch }}
-          ZEN_GENERATE_PGO_DATA: ${{ inputs.generate-pgo-data && '1' || '0' }}
         run: |
           export SURFER_PLATFORM="darwin"
           if [[ -n ${{ inputs.MOZ_BUILD_DATE }} ]];then
@@ -170,7 +150,6 @@ jobs:
           bash .github/workflows/src/release-build.sh
 
       - name: Package
-        if: ${{ !inputs.generate-pgo-data }}
         env:
           SURFER_COMPAT: ${{ matrix.arch }}
           ZEN_GA_DISABLE_PGO: true
@@ -184,7 +163,6 @@ jobs:
           rm -rf ~/.zen-keys
 
       - name: Rename artifacts
-        if: ${{ !inputs.generate-pgo-data }}
         run: |
           echo "Tarballing DMG"
           set -ex
@@ -194,7 +172,6 @@ jobs:
 
       - name: Upload dist dmg
         uses: actions/upload-artifact@v4
-        if: ${{ !inputs.generate-pgo-data }}
         with:
           retention-days: 1
           name: zen-${{ matrix.arch }}-apple-darwin-dist.dmg
@@ -202,7 +179,7 @@ jobs:
 
       - name: Upload host mar
         uses: actions/upload-artifact@v4
-        if: matrix.arch == 'aarch64' && !inputs.generate-pgo-data
+        if: matrix.arch == 'aarch64'
         with:
           retention-days: 1
           name: zen-macos-host-mar
@@ -210,16 +187,8 @@ jobs:
 
       - name: Upload platform.ini
         uses: actions/upload-artifact@v4
-        if: matrix.arch == 'x86_64' && !inputs.generate-pgo-data
+        if: matrix.arch == 'x86_64'
         with:
           retention-days: 1
           name: platform.ini
           path: ./platform.ini
-
-      - name: Upload PGO data
-        uses: actions/upload-artifact@v4
-        if: inputs.generate-pgo-data
-        with:
-          retention-days: 1
-          name: zen-macos-pgo-data-${{ matrix.arch }}
-          path: ./zen-macos-pgo-data

.github/workflows/src/release-build.sh

@@ -28,22 +28,3 @@ else
   export ZEN_RELEASE=1
   npm run build
 fi
-
-if test "$ZEN_GENERATE_PGO_DATA" = "1"; then
-  cd engine
-  export UPLOAD_PATH=../zen-macos-pgo-data
-  export MOZ_FETCHES_DIR=/Users/runner/.mozbuild
-  mkdir -p $UPLOAD_PATH
-
-  export JARLOG_FILE="en-US.log"
-
-  export LLVM_PROFDATA=$MOZ_FETCHES_DIR/clang/bin/llvm-profdata
-
-  set -v
-
-  ./mach python build/pgo/profileserver.py --binary obj-*-apple-darwin/dist/*.app/Contents/MacOS/zen
-
-  mv merged.profdata $UPLOAD_PATH/
-  mv $JARLOG_FILE $UPLOAD_PATH/
-  cd ..
-fi

configs/macos/mozconfig

@@ -14,6 +14,15 @@ if test "$ZEN_RELEASE"; then
   ac_add_options --enable-lto=cross,thin
 fi
 
+if test "$ZEN_RELEASE"; then
+  if test "$ZEN_GA_DISABLE_PGO"; then
+    export ZEN_DUMMY=1
+  else
+    export MOZ_PGO=1
+    ac_add_options MOZ_PGO=1
+  fi
+fi
+
 if test "$SURFER_COMPAT" = "x86_64"; then
   ac_add_options --target=x86_64-apple-darwin
 
@@ -41,18 +50,9 @@ fi
 # Keep using ld64 on PGO/LTO builds because of performance regressions when using lld.
 # Mozilla sets "MOZ_LD64_KNOWN_GOOD" to true when they do automated builds with PGO/LTO on macOS.
 # See https://searchfox.org/firefox-main/rev/e61d59b5c9a651fd7bf28043f87c0dc669833496/build/moz.configure/lto-pgo.configure#261
-export MOZ_LD64_KNOWN_GOOD=1
-ac_add_options --enable-linker=ld64
-
-if test "$ZEN_RELEASE"; then
-  if ! test "$ZEN_GA_DISABLE_PGO"; then
-    if test "$ZEN_GENERATE_PGO_DATA"; then
-      mk_add_options "export MOZ_AUTOMATION_PACKAGE_GENERATED_SOURCES=0"
-      ac_add_options --enable-profile-generate=cross
-    else
-      ac_add_options --enable-profile-use=cross
-      ac_add_options --with-pgo-profile-path=$(echo ~)/artifact/merged.profdata
-      ac_add_options --with-pgo-jarlog=$(echo ~)/artifact/en-US.log
-    fi
-  fi
-fi
+# export MOZ_LD64_KNOWN_GOOD=1
+# ac_add_options --enable-linker=ld64
+# 
+# if test "$ZEN_RELEASE"; then
+#   mk_add_options MOZ_MAKE_FLAGS="-j4"
+# fi

configs/windows/mozconfig

@@ -47,7 +47,9 @@ if test "$ZEN_CROSS_COMPILING"; then
     ac_add_options --enable-profile-generate=cross
   elif test "$SURFER_COMPAT" = "x86_64"; then
     # Dont use PGO on aarch64 builds and the ZEN_GA_DISABLE_PGO flag is not set
-    if ! test "$ZEN_GA_DISABLE_PGO"; then
+    if test "$ZEN_GA_DISABLE_PGO"; then
+      export ZEN_DUMMY=1
+    else
       ac_add_options --enable-profile-use=cross
       ac_add_options --with-pgo-profile-path=$(echo ~)/artifact/merged.profdata
       ac_add_options --with-pgo-jarlog=$(echo ~)/artifact/en-US.log

prefs/firefox/browser.yaml

@@ -69,6 +69,3 @@
 - name: browser.tabs.dragDrop.multiselectStacking
   value: false
   locked: true
-
-- name: browser.tabs.notes.enabled
-  value: false

prefs/zen/window-sync.yaml

@@ -10,6 +10,3 @@
 
 - name: zen.window-sync.prefer-unsynced-windows
   value: false
-
-- name: zen.window-sync.open-link-in-new-unsynced-window
-  value: true

src/browser/components/tabbrowser/content/tabbrowser-js.patch

@@ -1,5 +1,5 @@
 diff --git a/browser/components/tabbrowser/content/tabbrowser.js b/browser/components/tabbrowser/content/tabbrowser.js
-index 0eaca7a58e0026237b71b2ad515efe84d9e8c779..64b6fc581be1791ef9a750e03ab9a91c92325be3 100644
+index 0eaca7a58e0026237b71b2ad515efe84d9e8c779..f3966d85049735538b24424f42d4a690eaf7bbec 100644
 --- a/browser/components/tabbrowser/content/tabbrowser.js
 +++ b/browser/components/tabbrowser/content/tabbrowser.js
 @@ -398,6 +398,7 @@
@@ -591,7 +591,7 @@ index 0eaca7a58e0026237b71b2ad515efe84d9e8c779..64b6fc581be1791ef9a750e03ab9a91c
          Glean.browserTabclose.timeAnim.cancel(aTab._closeTimeAnimTimerId);
          aTab._closeTimeAnimTimerId = null;
 -        this._endRemoveTab(aTab);
-+        if (animate && !gReduceMotion && !(gZenUIManager.testingEnabled && !gZenUIManager.profilingEnabled)) {
++        if (animate && !gReduceMotion && !gZenUIManager.testingEnabled) {
 +          gZenVerticalTabsManager.animateTabClose(aTab, (animate && !gReduceMotion)).then(() => {
 +            this._endRemoveTab(aTab);
 +          });

src/browser/modules/URILoadingHelper-sys-mjs.patch

@@ -1,16 +1,8 @@
 diff --git a/browser/modules/URILoadingHelper.sys.mjs b/browser/modules/URILoadingHelper.sys.mjs
-index 9175fa820ad6bb75cd125fbfda2bf07d6dba4c90..62a1a62f304ec8c83e859196861025347e79ba46 100644
+index 9175fa820ad6bb75cd125fbfda2bf07d6dba4c90..f673cfd15289401ae425256016bf51303063e0b2 100644
 --- a/browser/modules/URILoadingHelper.sys.mjs
 +++ b/browser/modules/URILoadingHelper.sys.mjs
-@@ -225,6 +225,7 @@ function openInWindow(url, params, sourceWindow) {
-     features,
-     sa
-   );
-+  win._zenStartupSyncFlag = Services.prefs.getBoolPref('zen.window-sync.open-link-in-new-unsynced-window') ? 'unsynced' : 'synced';
- }
- 
- function openInCurrentTab(targetBrowser, url, uriObj, params) {
-@@ -542,7 +543,7 @@ export const URILoadingHelper = {
+@@ -542,7 +542,7 @@ export const URILoadingHelper = {
        // page. If a load request bounces off for the currently selected tab,
        // we'll open a new tab instead.
        let tab = w.gBrowser.getTabForBrowser(targetBrowser);
@@ -19,7 +11,7 @@ index 9175fa820ad6bb75cd125fbfda2bf07d6dba4c90..62a1a62f304ec8c83e85919686102534
          where = "tab";
          targetBrowser = null;
        } else if (
-@@ -972,7 +973,7 @@ export const URILoadingHelper = {
+@@ -972,7 +972,7 @@ export const URILoadingHelper = {
          ignoreQueryString || replaceQueryString,
          ignoreFragmentWhenComparing
        );
@@ -28,7 +20,7 @@ index 9175fa820ad6bb75cd125fbfda2bf07d6dba4c90..62a1a62f304ec8c83e85919686102534
        for (let i = 0; i < browsers.length; i++) {
          let browser = browsers[i];
          let browserCompare = cleanURL(
-@@ -1018,7 +1019,7 @@ export const URILoadingHelper = {
+@@ -1018,7 +1018,7 @@ export const URILoadingHelper = {
            }
  
            if (!doAdopt) {

src/browser/themes/shared/preferences/zen-preferences.css

@@ -7,10 +7,15 @@
 @namespace html 'http://www.w3.org/1999/xhtml';
 
 :root {
+  --zen-settings-secondary-background: light-dark(
+    #f2f4f4,
+    color-mix(in srgb, var(--zen-colors-tertiary) 50%, #0f0f0f 50%)
+  );
   --in-content-box-background: var(--zen-colors-tertiary) !important;
 }
 
 .main-content {
+  background: var(--zen-settings-secondary-background);
   padding-top: 60px !important;
 }
 
@@ -38,6 +43,35 @@ html|dialog {
   animation: dialogPopin 0.2s ease-out;
 }
 
+groupbox {
+  background: light-dark(white, color-mix(in srgb, var(--zen-primary-color) 2%, #1b1b1b 98%));
+  padding-inline: unset !important;
+  padding: 20px 30px !important;
+  margin-bottom: 0 !important;
+  position: relative;
+
+  /* add shadow just to the sides */
+  box-shadow: 0 0 2px 0 rgba(0, 0, 0, 0.1);
+}
+
+.subcategory + groupbox,
+#noFxaAccount,
+#hasFxaAccount {
+  border-top-left-radius: 5px;
+  border-top-right-radius: 5px;
+  margin-top: 5px;
+}
+
+groupbox:has(+ script),
+groupbox:last-of-type,
+groupbox#pane-experimental-featureGates,
+groupbox:has(+ .subcategory) {
+  border-bottom-left-radius: 5px !important;
+  border-bottom-right-radius: 5px !important;
+  /* add shadow just to bottom */
+  box-shadow: 0 0 2px 0 rgba(0, 0, 0, 0.1);
+}
+
 .sticky-inner-container {
   display: none !important;
 }

src/build/moz-configure/toolchain-configure.patch

@@ -1,13 +0,0 @@
-diff --git a/build/moz.configure/toolchain.configure b/build/moz.configure/toolchain.configure
-index 0fb4faa598072ccad47c376765a9433b40e27a6d..6ab448cc4202e5a3e871dfd753e95d76453758e5 100644
---- a/build/moz.configure/toolchain.configure
-+++ b/build/moz.configure/toolchain.configure
-@@ -1995,7 +1995,7 @@ def select_linker_tmpl(host_or_target):
-             # ensure consistent output.
-             env["LC_ALL"] = "C"
-             retcode, stdout, stderr = get_cmd_output(*cmd, env=env)
--            if retcode == 1 and "Logging ld64 options" in stderr:
-+            if retcode == 1 and "ld: unknown options: --version" in stderr:
-                 kind = "ld64"
- 
-             elif retcode != 0:

src/zen/common/modules/ZenStartup.mjs

@@ -5,6 +5,7 @@
 import checkForZenUpdates, {
   createWindowUpdateAnimation,
 } from 'chrome://browser/content/ZenUpdates.mjs';
+import { kDefaultSidebarWidth } from 'resource:///modules/ZenCustomizableUI.sys.mjs';
 
 class ZenStartup {
   #watermarkIgnoreElements = ['zen-toast-container'];
@@ -14,9 +15,11 @@ class ZenStartup {
 
   init() {
     this.openWatermark();
-    this.#initBrowserBackground();
-    this.#changeSidebarLocation();
-    this.#zenInitBrowserLayout();
+    gZenKeyboardShortcutsManager.beforeInit();
+    gZenWorkspaces.init().then(() => {
+      this.#initBrowserBackground();
+      this.#zenInitBrowserLayout();
+    });
   }
 
   #initBrowserBackground() {
@@ -36,7 +39,7 @@ class ZenStartup {
   #zenInitBrowserLayout() {
     if (this.#hasInitializedLayout) return;
     this.#hasInitializedLayout = true;
-    gZenKeyboardShortcutsManager.beforeInit();
+    this.#changeSidebarLocation();
     try {
       const kNavbarItems = ['nav-bar', 'PersonalToolbar'];
       const kNewContainerId = 'zen-appcontent-navbar-container';
@@ -54,16 +57,13 @@ class ZenStartup {
         document.getElementById('zen-appcontent-wrapper').prepend(deckTemplate);
       }
 
-      gZenWorkspaces.init();
-      setTimeout(() => {
-        gZenUIManager.init();
-        this.#checkForWelcomePage();
-      }, 0);
+      gZenUIManager.init();
+      this.#checkForWelcomePage();
     } catch (e) {
       console.error('ZenThemeModifier: Error initializing browser layout', e);
     }
     if (gBrowserInit.delayedStartupFinished) {
-      this.delayedStartupFinished();
+      this.#delayedStartupFinished();
     } else {
       Services.obs.addObserver(this, 'browser-delayed-startup-finished');
     }
@@ -74,14 +74,12 @@ class ZenStartup {
     // this window has finished painting and starting up.
     if (aTopic == 'browser-delayed-startup-finished' && aSubject == window) {
       Services.obs.removeObserver(this, 'browser-delayed-startup-finished');
-      this.delayedStartupFinished();
+      this.#delayedStartupFinished();
     }
   }
 
-  delayedStartupFinished() {
-    gZenWorkspaces.promiseInitialized.then(async () => {
-      await delayedStartupPromise;
-      await SessionStore.promiseAllWindowsRestored;
+  #delayedStartupFinished() {
+    gZenWorkspaces.promiseInitialized.then(() => {
       delete gZenUIManager.promiseInitialized;
       this.#initSearchBar();
       gZenCompactModeManager.init();
@@ -141,6 +139,20 @@ class ZenStartup {
     const browser = document.getElementById('browser');
     browser.prepend(gNavToolbox);
 
+    // Set a splitter to navigator-toolbox
+    const splitter = document.createXULElement('splitter');
+    splitter.setAttribute('id', 'zen-sidebar-splitter');
+    splitter.setAttribute('orient', 'horizontal');
+    splitter.setAttribute('resizebefore', 'sibling');
+    splitter.setAttribute('resizeafter', 'none');
+    gNavToolbox.insertAdjacentElement('afterend', splitter);
+
+    splitter.addEventListener('dblclick', (e) => {
+      if (e.button !== 0) return;
+      gNavToolbox.style.width = kDefaultSidebarWidth;
+      gNavToolbox.setAttribute('width', kDefaultSidebarWidth);
+    });
+
     const sidebarPanelWrapper = document.getElementById('tabbrowser-tabbox');
     for (let id of kElementsToAppend) {
       const elem = document.getElementById(id);
@@ -178,7 +190,7 @@ class ZenStartup {
 window.gZenStartup = new ZenStartup();
 
 window.addEventListener(
-  'MozBeforeInitialXULLayout',
+  'load',
   () => {
     gZenStartup.init();
   },

src/zen/common/modules/ZenUIManager.mjs

@@ -10,7 +10,6 @@ window.gZenUIManager = {
   _hoverPausedForExpand: false,
   _hasLoadedDOM: false,
   testingEnabled: Services.prefs.getBoolPref('zen.testing.enabled', false),
-  profilingEnabled: Services.prefs.getBoolPref('zen.testing.profiling.enabled', false),
 
   _lastClickPosition: null,
 
@@ -858,9 +857,7 @@ window.gZenVerticalTabsManager = {
       !aItem ||
       !gZenUIManager._hasLoadedDOM ||
       !aItem.isConnected ||
-      // We do want to do some animations during testing with profiling enabled
-      // so we can capture and improve them.
-      (gZenUIManager.testingEnabled && !gZenUIManager.profilingEnabled) ||
+      gZenUIManager.testingEnabled ||
       !gZenStartup.isReady ||
       aItem.group?.hasAttribute('split-view-group')
     ) {

src/zen/common/sys/ZenCustomizableUI.sys.mjs

@@ -4,6 +4,8 @@
 
 import { AppConstants } from 'resource://gre/modules/AppConstants.sys.mjs';
 
+export const kDefaultSidebarWidth = AppConstants.platform === 'macosx' ? '230px' : '186px';
+
 export const ZenCustomizableUI = new (class {
   constructor() {}
 
@@ -39,17 +41,8 @@ export const ZenCustomizableUI = new (class {
   }
 
   #addSidebarButtons(window) {
-    const kDefaultSidebarWidth = AppConstants.platform === 'macosx' ? '230px' : '186px';
     const toolbox = window.gNavToolbox;
 
-    // Set a splitter to navigator-toolbox
-    const splitter = window.document.createXULElement('splitter');
-    splitter.setAttribute('id', 'zen-sidebar-splitter');
-    splitter.setAttribute('orient', 'horizontal');
-    splitter.setAttribute('resizebefore', 'sibling');
-    splitter.setAttribute('resizeafter', 'none');
-    toolbox.insertAdjacentElement('afterend', splitter);
-
     const sidebarBox = window.MozXULElement.parseXULToFragment(`
       <toolbar id="zen-sidebar-top-buttons"
         fullscreentoolbar="true"
@@ -94,12 +87,6 @@ export const ZenCustomizableUI = new (class {
     toolbox.style.width = width;
     toolbox.setAttribute('width', width);
 
-    splitter.addEventListener('dblclick', (e) => {
-      if (e.button !== 0) return;
-      toolbox.style.width = kDefaultSidebarWidth;
-      toolbox.setAttribute('width', kDefaultSidebarWidth);
-    });
-
     const newTab = window.document.getElementById('vertical-tabs-newtab-button');
     newTab.classList.add('zen-sidebar-action-button');
 

src/zen/common/zenThemeModifier.js

@@ -9,148 +9,143 @@
  *
  * FOR ANY WEBSITE THAT WOULD NEED TO USE THE ACCENT COLOR, ETC
  */
-{
-  const { AppConstants } = ChromeUtils.importESModule(
-    'resource://gre/modules/AppConstants.sys.mjs'
-  );
 
-  const kZenThemePrefsList = [
-    'zen.theme.accent-color',
-    'zen.theme.border-radius',
-    'zen.theme.content-element-separation',
-  ];
-  const kZenMaxElementSeparation = 12;
+const kZenThemePrefsList = [
+  'zen.theme.accent-color',
+  'zen.theme.border-radius',
+  'zen.theme.content-element-separation',
+];
+const kZenMaxElementSeparation = 12;
+
+/**
+ * ZenThemeModifier controls the application of theme data to the browser,
+ * for example, it injects the accent color to the document. This is used
+ * because we need a way to apply the accent color without having to worry about
+ * shadow roots not inheriting the accent color.
+ *
+ * note: It must be a Firefox builtin page with access to the browser's configuration
+ *  and services.
+ */
+var ZenThemeModifier = {
+  _inMainBrowserWindow: false,
 
   /**
-   * ZenThemeModifier controls the application of theme data to the browser,
-   * for example, it injects the accent color to the document. This is used
-   * because we need a way to apply the accent color without having to worry about
-   * shadow roots not inheriting the accent color.
-   *
-   * note: It must be a Firefox builtin page with access to the browser's configuration
-   *  and services.
+   * Listen for theming updates from the LightweightThemeChild actor, and
+   * begin listening to changes in preferred color scheme.
    */
-  window.ZenThemeModifier = {
-    _inMainBrowserWindow: false,
+  init() {
+    this._inMainBrowserWindow = window.location.href == 'chrome://browser/content/browser.xhtml';
+    this.listenForEvents();
+    this.updateAllThemeBasics();
+  },
 
-    /**
-     * Listen for theming updates from the LightweightThemeChild actor, and
-     * begin listening to changes in preferred color scheme.
-     */
-    init() {
-      this._inMainBrowserWindow = window.location.href == 'chrome://browser/content/browser.xhtml';
-      this.listenForEvents();
-      this.updateAllThemeBasics();
-    },
+  listenForEvents() {
+    var handleEvent = this.handleEvent.bind(this);
+    // Listen for changes in the accent color and border radius
+    for (let pref of kZenThemePrefsList) {
+      Services.prefs.addObserver(pref, handleEvent);
+    }
 
-    listenForEvents() {
-      var handleEvent = this.handleEvent.bind(this);
-      // Listen for changes in the accent color and border radius
-      for (let pref of kZenThemePrefsList) {
-        Services.prefs.addObserver(pref, handleEvent);
-      }
+    // Add fullscreen listener to update the theme when going in and out of fullscreen
+    const eventsForSeparation = [
+      'ZenViewSplitter:SplitViewDeactivated',
+      'ZenViewSplitter:SplitViewActivated',
+      'fullscreen',
+      'ZenCompactMode:Toggled',
+    ];
+    const separationHandler = this.updateElementSeparation.bind(this);
+    for (let eventName of eventsForSeparation) {
+      window.addEventListener(eventName, separationHandler);
+    }
 
-      // Add fullscreen listener to update the theme when going in and out of fullscreen
-      const eventsForSeparation = [
-        'ZenViewSplitter:SplitViewDeactivated',
-        'ZenViewSplitter:SplitViewActivated',
-        'fullscreen',
-        'ZenCompactMode:Toggled',
-      ];
-      const separationHandler = this.updateElementSeparation.bind(this);
-      for (let eventName of eventsForSeparation) {
-        window.addEventListener(eventName, separationHandler);
-      }
-
-      window.addEventListener(
-        'unload',
-        () => {
-          for (let pref of kZenThemePrefsList) {
-            Services.prefs.removeObserver(pref, handleEvent);
-          }
-          for (let eventName of eventsForSeparation) {
-            window.removeEventListener(eventName, separationHandler);
-          }
-        },
-        { once: true }
-      );
-    },
-
-    handleEvent() {
-      // note: even might be undefined, but we shoudnt use it!
-      this.updateAllThemeBasics();
-    },
-
-    /**
-     * Update all theme basics, like the accent color.
-     */
-    async updateAllThemeBasics() {
-      this.updateAccentColor();
-      this.updateBorderRadius();
-      this.updateElementSeparation();
-    },
-
-    updateBorderRadius() {
-      const borderRadius = Services.prefs.getIntPref('zen.theme.border-radius', -1);
-
-      // -1 is the default value, will use platform-native values
-      // otherwise, use the custom value
-      if (borderRadius == -1) {
-        if (AppConstants.platform == 'macosx') {
-          const targetRadius = window.matchMedia('(-moz-mac-tahoe-theme)').matches ? 15 : 10;
-          document.documentElement.style.setProperty('--zen-border-radius', targetRadius + 'px');
-        } else if (AppConstants.platform == 'linux') {
-          // Linux uses GTK CSD titlebar radius, default to 8px
-          document.documentElement.style.setProperty(
-            '--zen-border-radius',
-            'env(-moz-gtk-csd-titlebar-radius, 8px)'
-          );
-        } else {
-          // Windows defaults to 8px
-          document.documentElement.style.setProperty('--zen-border-radius', '8px');
+    window.addEventListener(
+      'unload',
+      () => {
+        for (let pref of kZenThemePrefsList) {
+          Services.prefs.removeObserver(pref, handleEvent);
         }
+        for (let eventName of eventsForSeparation) {
+          window.removeEventListener(eventName, separationHandler);
+        }
+      },
+      { once: true }
+    );
+  },
+
+  handleEvent() {
+    // note: even might be undefined, but we shoudnt use it!
+    this.updateAllThemeBasics();
+  },
+
+  /**
+   * Update all theme basics, like the accent color.
+   */
+  async updateAllThemeBasics() {
+    this.updateAccentColor();
+    this.updateBorderRadius();
+    this.updateElementSeparation();
+  },
+
+  updateBorderRadius() {
+    const borderRadius = Services.prefs.getIntPref('zen.theme.border-radius', -1);
+
+    // -1 is the default value, will use platform-native values
+    // otherwise, use the custom value
+    if (borderRadius == -1) {
+      if (AppConstants.platform == 'macosx') {
+        const targetRadius = window.matchMedia('(-moz-mac-tahoe-theme)').matches ? 15 : 10;
+        document.documentElement.style.setProperty('--zen-border-radius', targetRadius + 'px');
+      } else if (AppConstants.platform == 'linux') {
+        // Linux uses GTK CSD titlebar radius, default to 8px
+        document.documentElement.style.setProperty(
+          '--zen-border-radius',
+          'env(-moz-gtk-csd-titlebar-radius, 8px)'
+        );
       } else {
-        // Use the overridden value
-        document.documentElement.style.setProperty('--zen-border-radius', borderRadius + 'px');
+        // Windows defaults to 8px
+        document.documentElement.style.setProperty('--zen-border-radius', '8px');
       }
-    },
+    } else {
+      // Use the overridden value
+      document.documentElement.style.setProperty('--zen-border-radius', borderRadius + 'px');
+    }
+  },
 
-    updateElementSeparation() {
-      const kMinElementSeparation = 0.1; // in px
-      let separation = this.elementSeparation;
-      if (
-        document.documentElement.hasAttribute('inFullscreen') &&
-        window.gZenCompactModeManager?.preference &&
-        !document.getElementById('tabbrowser-tabbox')?.hasAttribute('zen-split-view') &&
-        Services.prefs.getBoolPref('zen.view.borderless-fullscreen', true)
-      ) {
-        separation = 0;
-      }
-      // In order to still use it on fullscreen, even if it's 0px, add .1px (almost invisible)
-      separation = Math.max(kMinElementSeparation, separation);
-      document.documentElement.style.setProperty('--zen-element-separation', separation + 'px');
-      if (separation == kMinElementSeparation) {
-        document.documentElement.setAttribute('zen-no-padding', true);
-      } else {
-        document.documentElement.removeAttribute('zen-no-padding');
-      }
-    },
+  updateElementSeparation() {
+    const kMinElementSeparation = 0.1; // in px
+    let separation = this.elementSeparation;
+    if (
+      document.documentElement.hasAttribute('inFullscreen') &&
+      window.gZenCompactModeManager?.preference &&
+      !document.getElementById('tabbrowser-tabbox')?.hasAttribute('zen-split-view') &&
+      Services.prefs.getBoolPref('zen.view.borderless-fullscreen', true)
+    ) {
+      separation = 0;
+    }
+    // In order to still use it on fullscreen, even if it's 0px, add .1px (almost invisible)
+    separation = Math.max(kMinElementSeparation, separation);
+    document.documentElement.style.setProperty('--zen-element-separation', separation + 'px');
+    if (separation == kMinElementSeparation) {
+      document.documentElement.setAttribute('zen-no-padding', true);
+    } else {
+      document.documentElement.removeAttribute('zen-no-padding');
+    }
+  },
 
-    get elementSeparation() {
-      return Math.min(
-        Services.prefs.getIntPref('zen.theme.content-element-separation'),
-        kZenMaxElementSeparation
-      );
-    },
+  get elementSeparation() {
+    return Math.min(
+      Services.prefs.getIntPref('zen.theme.content-element-separation'),
+      kZenMaxElementSeparation
+    );
+  },
 
-    /**
-     * Update the accent color.
-     */
-    updateAccentColor() {
-      const accentColor = Services.prefs.getStringPref('zen.theme.accent-color');
-      document.documentElement.style.setProperty('--zen-primary-color', accentColor);
-    },
-  };
+  /**
+   * Update the accent color.
+   */
+  updateAccentColor() {
+    const accentColor = Services.prefs.getStringPref('zen.theme.accent-color');
+    document.documentElement.style.setProperty('--zen-primary-color', accentColor);
+  },
+};
 
-  if (typeof Services !== 'undefined') ZenThemeModifier.init();
-}
+if (typeof Services !== 'undefined') ZenThemeModifier.init();

src/zen/compact-mode/ZenCompactMode.mjs

@@ -467,8 +467,6 @@ window.gZenCompactModeManager = {
                     });
                   }
 
-                  this.sidebar.style.removeProperty('margin-right');
-                  this.sidebar.style.removeProperty('margin-left');
                   this.sidebar.style.removeProperty('transition');
                   this.sidebar.style.removeProperty('transform');
                   this.sidebar.style.removeProperty('point-events');

src/zen/sessionstore/ZenSessionManager.sys.mjs

@@ -15,16 +15,9 @@ ChromeUtils.defineESModuleGetters(lazy, {
   SessionSaver: 'resource:///modules/sessionstore/SessionSaver.sys.mjs',
   setTimeout: 'resource://gre/modules/Timer.sys.mjs',
   gWindowSyncEnabled: 'resource:///modules/zen/ZenWindowSync.sys.mjs',
-  DeferredTask: 'resource://gre/modules/DeferredTask.sys.mjs',
 });
 
 XPCOMUtils.defineLazyPreferenceGetter(lazy, 'gShouldLog', 'zen.session-store.log', true);
-XPCOMUtils.defineLazyPreferenceGetter(
-  lazy,
-  'gMaxSessionBackups',
-  'zen.session-store.max-backups',
-  10
-);
 
 // Note that changing this hidden pref will make the previous session file
 // unused, causing a new session file to be created on next write.
@@ -37,10 +30,6 @@ const MIGRATION_PREF = 'zen.ui.migration.session-manager-restore';
 // 'browser.startup.page' preference value to resume the previous session.
 const BROWSER_STARTUP_RESUME_SESSION = 3;
 
-// The amount of time (in milliseconds) to wait for our backup regeneration
-// debouncer to kick off a regeneration.
-const REGENERATION_DEBOUNCE_RATE_MS = 20 * 60 * 1000; // 20 minutes
-
 /**
  * Class representing the sidebar object stored in the session file.
  * This object holds all the data related to tabs, groups, folders
@@ -69,18 +58,13 @@ export class nsZenSessionManager {
    * @type {nsZenSidebarObject}
    */
   #sidebarObject = new nsZenSidebarObject();
-  /**
-   * A deferred task to create backups of the session file.
-   */
-  #deferredBackupTask = null;
 
   // Called from SessionComponents.manifest on app-startup
   init() {
-    this.log('Initializing session manager');
     let profileDir = Services.dirsvc.get('ProfD', Ci.nsIFile).path;
     let backupFile = null;
     if (SHOULD_BACKUP_FILE) {
-      backupFile = PathUtils.join(this.#backupFolderPath, FILE_NAME);
+      backupFile = PathUtils.join(profileDir, 'zen-sessions-backup', FILE_NAME);
     }
     let filePath = PathUtils.join(profileDir, FILE_NAME);
     this.#file = new JSONFile({
@@ -88,9 +72,6 @@ export class nsZenSessionManager {
       compression: SHOULD_COMPRESS_FILE ? 'lz4' : undefined,
       backupFile,
     });
-    this.#deferredBackupTask = new lazy.DeferredTask(async () => {
-      await this.#createBackupsIfNeeded();
-    }, REGENERATION_DEBOUNCE_RATE_MS);
   }
 
   log(...args) {
@@ -99,11 +80,6 @@ export class nsZenSessionManager {
     }
   }
 
-  get #backupFolderPath() {
-    let profileDir = Services.dirsvc.get('ProfD', Ci.nsIFile).path;
-    return PathUtils.join(profileDir, 'zen-sessions-backup');
-  }
-
   /**
    * Gets the spaces data from the Places database for migration.
    * This is only called once during the first run after updating
@@ -268,66 +244,9 @@ export class nsZenSessionManager {
     // quitting the app.
     this.#file.data = this.#sidebar;
     this.#file.saveSoon();
-    this.#debounceRegeneration();
     this.log(`Saving Zen session data with ${this.#sidebar.tabs?.length || 0} tabs`);
   }
 
-  /**
-   * Called when the last known backup should be deleted and a new one
-   * created. This uses the #deferredBackupTask to debounce clusters of
-   * events that might cause such a regeneration to occur.
-   */
-  #debounceRegeneration() {
-    this.#deferredBackupTask.disarm();
-    this.#deferredBackupTask.arm();
-  }
-
-  /**
-   * Creates backups of the session file if needed. We only keep
-   * a limited number of backups to avoid using too much disk space.
-   * The way we are doing this is by replacing the file for today's
-   * date if it already exists, otherwise we create a new one.
-   * We then delete the oldest backups if we exceed the maximum
-   * number of backups allowed.
-   *
-   * We run the next backup creation after a delay or when idling,
-   * to avoid blocking the main thread during session saves.
-   */
-  async #createBackupsIfNeeded() {
-    if (!SHOULD_BACKUP_FILE) {
-      return;
-    }
-    try {
-      const today = new Date();
-      const backupFolder = this.#backupFolderPath;
-      await IOUtils.makeDirectory(backupFolder, {
-        ignoreExisting: true,
-        createAncestors: true,
-      });
-      const todayFileName = `zen-sessions-${today.getFullYear()}-${(today.getMonth() + 1)
-        .toString()
-        .padStart(2, '0')}-${today.getDate().toString().padStart(2, '0')}.json${
-        SHOULD_COMPRESS_FILE ? 'lz4' : ''
-      }`;
-      const todayFilePath = PathUtils.join(backupFolder, todayFileName);
-      const sessionFilePath = this.#file.path;
-      this.log(`Backing up session file to ${todayFileName}`);
-      await IOUtils.copy(sessionFilePath, todayFilePath, { noOverwrite: false });
-      // Now we need to check if we have exceeded the maximum
-      // number of backups allowed, and delete the oldest ones
-      // if needed.
-      let files = await IOUtils.getChildren(backupFolder);
-      files = files.filter((file) => file.startsWith('zen-sessions-')).sort();
-      for (let i = 0; i < files.length - lazy.gMaxSessionBackups; i++) {
-        const fileToDelete = PathUtils.join(backupFolder, files[i].name);
-        this.log(`Deleting old backup file ${files[i].name}`);
-        await IOUtils.remove(fileToDelete);
-      }
-    } catch (e) {
-      console.error('ZenSessionManager: Failed to create session file backups', e);
-    }
-  }
-
   /**
    * Saves the session data for a closed window if it meets the criteria.
    * See SessionStoreInternal.maybeSaveClosedWindow for more details.

src/zen/workspaces/ZenWorkspaces.mjs

@@ -777,7 +777,12 @@ class nsZenWorkspaces {
   }
 
   get workspaceEnabled() {
-    return this.shouldHaveWorkspaces && !window.closed;
+    if (typeof this._workspaceEnabled === 'undefined') {
+      this._workspaceEnabled =
+        this.shouldHaveWorkspaces &&
+        !Services.prefs.getBoolPref('zen.testing.profiling.enabled', false);
+    }
+    return this._workspaceEnabled && !window.closed;
   }
 
   getActiveWorkspaceFromCache() {