Flutter performance optimizer

Skill Desquared/agents-rules-skills/skills/flutter-performance-optimizer

Use when Flutter UI has jank, slow scrolling, excessive rebuilds, or memory leaks. Also use when optimizing lists, animations, or complex widget trees, or when the user asks about Flutter rendering performance.From its SKILL.md

Install

npx -y skills add Desquared/agents-rules-skills --skill flutter-performance-optimizer

Assembled from the repository path, not quoted from the project. Check it against their README if it does not work.

One thing to look at

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SKILL.md

1.6 KB, as published. Nobody here has run it

Optimization Skill

Quick Wins

// 1. const: const Text('Title') vs Text('Title')

// 2. Narrow BlocBuilder: Scaffold(body: BlocBuilder(...)) 
//    vs BlocBuilder(builder: (ctx, state) => Scaffold(...))

// 3. buildWhen: buildWhen: (prev, curr) => prev.data != curr.data

// 4. ListView.builder vs ListView(children: [])

// 5. Keys: key: ValueKey(items[i].id)

// 6. Batch API:
// ❌ for (item in items) await api.fetch(item.id);
// ✅ await Future.wait(items.map((i) => api.fetch(i.id)));
// ✅✅ await api.fetchBatch(ids);

// 7. Debounce:
Timer? _debounce;
void onSearchChanged(String q) {
  _debounce?.cancel();
  _debounce = Timer(Duration(milliseconds: 300), () => _search(q));
}

// 8. Heavy work: compute(_heavy, data) in Bloc, NOT in build()

// 9. Images: CachedNetworkImage with width/height

// 10. Memory leaks:
@override Future<void> close() { _controller.close(); return super.close(); }
@override void dispose() { _timer?.cancel(); super.dispose(); }

Common Issues

BlocBuilder wraps entire screen → Narrow scope
Missing const → Add const
No buildWhen → Filter rebuilds
ListView without .builder → Use .builder
Sequential API calls → Batch or parallel
Heavy computation in build() → Move to Bloc/isolate
Streams/timers not closed → Dispose properly

Diagnostics

flutter run --profile --trace-skia
# DevTools → Memory, Performance