Performance optimization in React Native requires a different toolkit than web development. Here are the optimizations that deliver the biggest impact based on our production profiling across 12 client apps.
JavaScript Thread
The JS thread handles business logic and React rendering. Keep it lean by memoizing expensive computations, using FlashList instead of FlatList for long lists, and deferring non-critical work with InteractionManager.runAfterInteractions().
Native Thread
Animations should run on the native thread using Reanimated 3. Avoid Animated API for anything beyond simple fades. Layout animations with entering and exiting modifiers provide polished transitions without JS bridge overhead.
Bundle Size
Enable Hermes engine for faster startup. Use inline requires for large modules. Analyze your bundle with react-native-bundle-visualizer and eliminate duplicate dependencies.
Image Optimization
Use FastImage for caching and progressive loading. Serve appropriately sized images — a 4000px photo displayed at 200px wastes memory and decode time. Implement blurhash placeholders for perceived performance.