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majiayu000/claude-skill-registry/flutter-performance

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PublishedMarch 9, 2026 at 02:32 PM

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description: "Flutter performance: DevTools profiling, widget optimization, memory management, const widgets. Use when optimizing render performance or debugging jank." version: "1.0.0" updated: "2026-01-07"

Flutter Performance

Commands

bash

flutter run --profile  # Required for profiling
flutter pub global run devtools

Targets

Target	Threshold
60 FPS	16.67ms/frame
Cold start	< 2s

Widget Optimization

Const Constructors

dart

// GOOD
const Column(children: [Text('Static'), Icon(Icons.star)])

Extract Widgets

dart

// GOOD: Only counter rebuilds
Column(
  children: [
    const ExpensiveWidget(),  // no rebuild
    _Counter(),               // isolated state
  ],
)

RepaintBoundary

dart

RepaintBoundary(child: AnimatedWidget())

Build Optimization

dart

// BAD: compute in build
final sorted = items..sort();
 
// GOOD: compute once
late List<Item> _sorted;
void initState() { _sorted = items..sort(); }

Memory Management

dart

@override
void dispose() {
  _animController.dispose();
  _textController.dispose();
  _subscription?.cancel();
  super.dispose();
}
 
// Check mounted
if (!mounted) return;
setState(() => _data = data);

Lists

dart

// Use builder
ListView.builder(itemCount: items.length, itemBuilder: ...)
 
// Fixed extent
ListView.builder(itemExtent: 72, ...)
 
// Keys
ValueKey(item.id)

Images

dart

CachedNetworkImage(
  imageUrl: url,
  memCacheWidth: 200,
  memCacheHeight: 200,
)

Checklist

[ ] Profiled in profile mode
[ ] No expensive ops in build()
[ ] Const constructors used
[ ] ListView.builder for lists
[ ] Controllers disposed
[ ] Check mounted before setState

Related Skills

flutter-animations: Animation performance
flutter-code-quality: Static analysis

All versions