| name | app-performance |
| description | Diagnose and improve Expo/React Native mobile performance including startup, lists, images, animations, JS thread work, bundle size, network retries, and production-build profiling. |
App Performance
Use this skill when the user reports slow startup, janky scrolling, heavy images, animation stutter, battery/network waste, memory pressure, or wants a performance review of a React Native app.
Required Context
- Read
rules/mobile-performance.md.
- Read
specs/mobile-performance.md for measurement and optimization patterns.
- For list or rendering issues, also read
rules/react-native.md.
Workflow
- Reproduce on the closest target device and build type.
- Identify the bottleneck category: startup, JS render, list virtualization, image/media, animation, network, native module, or package size.
- Make one focused optimization.
- Re-measure on the same device/build.
- Record the before/after signal in the task or PR.
Checks
- No unbounded
ScrollView for growing lists.
- No expensive render-time parsing or formatting.
- Images have stable dimensions and appropriate size.
- Retry/refresh behavior has limits and backoff.
- Performance claims are based on measurement, not intuition.
