React Native has evolved significantly with its new architecture. The new architecture features the Fabric renderer and TurboModules, replacing the old bridge system. Fabric allows synchronous communication between JavaScript and native threads, improving performance for animations and gestures. TurboModules enable lazy loading of native modules, reducing app startup time. The new architecture also introduces JSI (JavaScript Interface) for direct native method calls without serialization overhead. React Native uses a JavaScript thread for business logic, a native thread for UI rendering, and a shadow thread for layout calculations. The Hermes engine, now the default, provides faster startup and reduced memory usage. Code sharing between iOS and Android reaches up to 90%, significantly reducing development time. The fast refresh feature enables instant feedback during development. For state management, options include Redux, Zustand, and React Context. Navigation is handled by React Navigation library. For performance optimization, use FlatList instead of ScrollView for large lists, implement image caching, and avoid unnecessary re-renders. React Native remains a top choice for cross-platform mobile development.