The Fabric renderer in React Native improves UI performance by enabling synchronous rendering and reducing bridge overhead. It helps achieve smoother animations closer to 60fps by allowing direct communication between JavaScript and native views. This reduces frame drops and lowers CPU usage, which also helps save battery life on mobile devices.
To get the best from Fabric, keep your UI components simple and avoid heavy computations during rendering. Use React Native's new architecture features like TurboModules and Codegen to minimize bridge calls. Also, batch updates and avoid unnecessary re-renders by using memoization and hooks like useMemo and useCallback. Profiling with React DevTools and Flipper helps spot bottlenecks.
Enabling Fabric may slightly increase your app bundle size due to additional native code and new architecture dependencies. However, this increase is usually small (a few MB) and is offset by faster UI rendering and smoother user experience. Startup time can improve because Fabric allows more efficient initialization of UI components.
Fabric is designed to work on both iOS and Android, but implementation details differ. On iOS, Fabric integrates with UIKit and SwiftUI components, while on Android it works with Jetpack Compose and native views. The bridge improvements and synchronous rendering are consistent, but native module setup and lifecycle events vary by platform. Testing on both platforms is essential.
Using Fabric does not change app store requirements, but ensure your app complies with performance and stability guidelines. Apple's App Store expects smooth UI and no crashes, which Fabric helps achieve. Google Play requires apps to be responsive and efficient. Also, keep your app size reasonable and avoid excessive background CPU usage to pass store reviews.
If your screen is slow despite using Fabric, you might have heavy synchronous work blocking the UI thread, or too many unnecessary re-renders. Check for expensive JavaScript computations during render, large images loading without optimization, or excessive bridge calls. Use profiling tools to identify and fix these bottlenecks.