fix performance issues

apps/weblibre/lib/features/geckoview/features/search/presentation/widgets/empty_state/top_sites_section.dart

@@ -18,6 +18,7 @@
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 import 'package:flutter/material.dart';
+import 'package:flutter/rendering.dart';
 import 'package:flutter_hooks/flutter_hooks.dart';
 import 'package:flutter_material_design_icons/flutter_material_design_icons.dart'
     show MdiIcons;
@@ -68,6 +69,44 @@ _TopSitesGridLayout _resolveGridLayout(double width) {
   );
 }
 
+/// Responsive grid delegate that resolves the column count from the available
+/// cross-axis extent at the *render* layer (in [getLayout]), mirroring
+/// [_resolveGridLayout].
+///
+/// This replaces a `SliverLayoutBuilder`, whose builder re-runs (and rebuilds
+/// the entire grid subtree) on every [SliverConstraints] change — i.e. on every
+/// scroll and every keyboard-inset animation frame — which rebuilt all
+/// top-site tiles each frame. The delegate recomputes grid metrics on layout
+/// without rebuilding any widgets.
+class _TopSitesGridDelegate extends SliverGridDelegate {
+  const _TopSitesGridDelegate();
+
+  @override
+  SliverGridLayout getLayout(SliverConstraints constraints) {
+    final layout = _resolveGridLayout(constraints.crossAxisExtent);
+    final crossAxisCount = layout.crossAxisCount;
+
+    final usableCrossAxisExtent =
+        (constraints.crossAxisExtent -
+                _gridCrossAxisSpacing * (crossAxisCount - 1))
+            .clamp(0.0, double.infinity);
+    final childCrossAxisExtent = usableCrossAxisExtent / crossAxisCount;
+    final childMainAxisExtent = childCrossAxisExtent / layout.childAspectRatio;
+
+    return SliverGridRegularTileLayout(
+      crossAxisCount: crossAxisCount,
+      mainAxisStride: childMainAxisExtent + _gridMainAxisSpacing,
+      crossAxisStride: childCrossAxisExtent + _gridCrossAxisSpacing,
+      childMainAxisExtent: childMainAxisExtent,
+      childCrossAxisExtent: childCrossAxisExtent,
+      reverseCrossAxis: axisDirectionIsReversed(constraints.crossAxisDirection),
+    );
+  }
+
+  @override
+  bool shouldRelayout(_TopSitesGridDelegate oldDelegate) => false;
+}
+
 class TopSitesSection extends HookConsumerWidget {
   final void Function(Uri uri) onUriSelected;
 
@@ -156,16 +195,8 @@ class _TopSitesGrid extends ConsumerWidget {
 
     return SliverPadding(
       padding: const EdgeInsets.symmetric(horizontal: 12.0, vertical: 4.0),
-      sliver: SliverLayoutBuilder(
-        builder: (context, constraints) {
-          final layout = _resolveGridLayout(constraints.crossAxisExtent);
-          return SliverGrid.builder(
-            gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
-              crossAxisCount: layout.crossAxisCount,
-              mainAxisSpacing: _gridMainAxisSpacing,
-              crossAxisSpacing: _gridCrossAxisSpacing,
-              childAspectRatio: layout.childAspectRatio,
-            ),
+      sliver: SliverGrid.builder(
+        gridDelegate: const _TopSitesGridDelegate(),
         itemCount: displayItems.length,
         itemBuilder: (context, index) {
           final item = displayItems[index];
@@ -177,8 +208,6 @@ class _TopSitesGrid extends ConsumerWidget {
             onRemove: () => _removeItem(context, ref, item),
           );
         },
-          );
-        },
       ),
     );
   }

apps/weblibre/lib/features/geckoview/features/tabs/utils/container_colors.dart

@@ -84,6 +84,24 @@ class ContainerColors {
   static const double surfaceHighAlpha = 0.28;
   static const double outlineBorderAlpha = 0.5;
 
+  /// Cache of seed schemes keyed by `(seed color, brightness)`.
+  ///
+  /// [ColorScheme.fromSeed] runs the full HCT tonal-palette solver, which is
+  /// very expensive (the `material_color_utilities` `HctSolver`/`DynamicColor`
+  /// math dominated CPU profiles at hundreds of ms). The result is a pure
+  /// function of its seed colour and brightness, so generating it once per
+  /// distinct `(color, brightness)` and reusing it across rebuilds removes the
+  /// cost entirely — previously seed mode computed a *full* scheme up to four
+  /// times per [palette] call, for every chip, on every rebuild.
+  static final Map<(int, Brightness), ColorScheme> _seedSchemeCache = {};
+
+  static ColorScheme _seedScheme(Color seedColor, Brightness brightness) {
+    return _seedSchemeCache.putIfAbsent(
+      (seedColor.toARGB32(), brightness),
+      () => ColorScheme.fromSeed(seedColor: seedColor, brightness: brightness),
+    );
+  }
+
   static ContainerColorPalette palette(
     BuildContext context,
     Color color, {
@@ -93,30 +111,22 @@ class ContainerColors {
     final appScheme = theme.colorScheme;
     final fullColor = fullOpacity(color);
 
+    final seedScheme = useCustomColor
+        ? null
+        : _seedScheme(fullColor, theme.brightness);
+
     final containerColor = useCustomColor
         ? fullColor
-        : ColorScheme.fromSeed(
-            seedColor: fullColor,
-            brightness: theme.brightness,
-          ).primaryContainer;
+        : seedScheme!.primaryContainer;
     final accentColor = useCustomColor
         ? _shiftTone(fullColor, theme.brightness)
-        : ColorScheme.fromSeed(
-            seedColor: fullColor,
-            brightness: theme.brightness,
-          ).primary;
+        : seedScheme!.primary;
     final onContainerColor = useCustomColor
         ? _contrastingForeground(containerColor)
-        : ColorScheme.fromSeed(
-            seedColor: fullColor,
-            brightness: theme.brightness,
-          ).onPrimaryContainer;
+        : seedScheme!.onPrimaryContainer;
     final onAccentColor = useCustomColor
         ? _contrastingForeground(accentColor)
-        : ColorScheme.fromSeed(
-            seedColor: fullColor,
-            brightness: theme.brightness,
-          ).onPrimary;
+        : seedScheme!.onPrimary;
 
     final surfaceColor = Color.alphaBlend(
       containerColor.withValues(alpha: surfaceAlpha),