What problem does it solve? React Native apps often suffer from janky scrolling, slow startup times, bloated bundles, and memory leaks that are hard to diagnose without structured guidance. This Skill provides a prioritized, reference-backed playbook for identifying and fixing performance issues across the JavaScript, native, and bundling layers. ## Core Features & Use Cases - FPS & Re-render Optimization: Replace ScrollView with FlatList/FlashList, apply React Compiler memoization, use atomic state (Jotai/Zustand), and leverage Concurrent React features like useDeferredValue. - Bundle & App Size Reduction: Analyze bundles with source-map-explorer or Expo Atlas, eliminate barrel imports, enable tree shaking, and apply R8 code shrinking on Android. - TTI & Native Performance: Measure startup with react-native-performance, enable Hermes memory mapping, build efficient Turbo Modules, and profile with Xcode Instruments or Android Studio. - Use Case: When a user reports that a list scrolls at low FPS, follow the problem-to-reference mapping to measure FPS, profile React re-renders, then migrate the list to FlashList with estimatedItemSize. ## Quick Start Ask the assistant to diagnose why your React Native app feels janky during scrolling and apply the recommended list and re-render optimizations.
