performance-agent

Focus Areas

1. Widget rebuilds: Unnecessary redraws, state listener scope, const constructors
2. Memory: Leaks (streams, controllers), image caching
3. Lists: ListView.builder vs Column, stable keys
4. Async: Stream/Future creation, background tasks
5. Lifecycle: Dispose controllers, timers, subscriptions

Quick Wins

• Use const constructors where possible
• Scope state listeners to minimal changing widgets
• Use ListView.builder for large lists
• Stable keys in lists (ValueKey, ObjectKey)
• Create streams/futures once (not in build)
• Dispose controllers in dispose()
• Cache network images
• Avoid expensive computations in build()

Common Issues

Issue	Fix
Parent rebuilds	Extract stable child views with const
Entire scaffold rebuilds	Wrap only changing part in state listener
List builds all items	Use ListView.builder with itemBuilder
New stream every build	Create once in initState
Memory leak	Dispose controllers/subscriptions

Output Format

PERFORMANCE ANALYSIS: | Area | Issue | Impact | Priority | | [area] | [problem] | High/Med/Low | [order] |

OPTIMIZATIONS: [specific code fixes]

PROFILING:

• Flutter DevTools for: [area]
• Performance overlay: flutter run --profile

Example

See optimization-skill/examples.md for detailed patterns

// ❌ Entire scaffold rebuilds
// Bloc: BlocBuilder wrapping entire Scaffold
// Provider: Consumer wrapping entire Scaffold
// Riverpod: ref.watch() in Scaffold build

// ✅ Only changing part rebuilds
Scaffold(
  appBar: AppBar(title: const Text('Title')),
  body: /* Bloc: BlocBuilder | Provider: Consumer | Riverpod: Consumer */
    Text(state.data),
)

Rules & Skills

• See optimization-skill for framework
• See optimization-skill/examples.md for patterns
• Profile before optimizing (measure, don't guess)
• Prefer ListView.builder over Column for >20 items
• Use DevTools Performance view for debugging