React Native's new architecture — Fabric, TurboModules, and the JSI layer underneath — is no longer an experimental toggle. In 2026, if you start a new project, you start on the new arch. If you have a mature app, you've been migrating for a year. The question is no longer "should we migrate" but "how do we finish the migration cleanly."

The old architecture was a three-layer cake: JavaScript, the bridge, and native modules. Every call across the bridge serialized data, queued messages, and synchronized on a single thread. It worked, but it was never going to be fast enough for 120Hz ProMotion displays or for the kind of complex gestures users now expect from native-feeling apps.

The new architecture removes the bridge entirely. The JSI (JavaScript Interface) is a C++ layer that lets JavaScript hold direct references to C++ objects and call methods on them synchronously. No more serialization, no more async queue, no more waiting for the next bridge tick to see your UI update.

What Fabric changes

Fabric is the new renderer. It's a concurrent renderer — it can prepare UI updates in a background thread and commit them in a way that doesn't block the main thread. This means smoother scrolling and more responsive gestures, even under heavy load.

For most apps, the visible result is that scroll lists feel more like UIKit and less like a webview. Frame drops during gestures drop dramatically. Animations stay smooth while you're also parsing a 5MB JSON response on the JS thread.

Fabric also enables synchronous layout — you can call measure() and get a real answer immediately, not a callback. This matters for libraries that need precise layout information, like react-native-reanimated's worklet-driven animations.

What TurboModules change

TurboModules replace the old NativeModules system. They're lazy-loaded (only loaded when actually called) and they expose a strongly-typed interface that TypeScript can verify at build time. The days of NativeModules.SomeModule.doSomething() returning any are finally over.

The biggest practical win is startup time. Old NativeModules all got initialized at app launch, even if you never used them. A typical app with 15-20 native modules was paying 200-400ms of startup time for code that never ran. TurboModules load on first use. The win scales with the number of modules you have.

The spec is written once, in TypeScript. The build process generates the Swift and Kotlin interfaces from that spec. You implement the methods in each platform, and the framework guarantees the types match.

What stays the same

The component model. Your View, Text, and Pressable are still the same. Your state management still lives in JavaScript. Your navigation library still works the same way. The new architecture is invisible to 90% of your application code.

The biggest visible breakage is in libraries that haven't migrated. If you're using a third-party library that still depends on the old bridge, you'll either need to upgrade the library or fork it.

How to migrate

The migration is usually: enable the new arch in your build config, run the app, see what breaks, and fix the third-party libraries that haven't migrated.

The official migration guide walks through the steps. The hardest part is usually the third-party libraries. As of 2026, most popular libraries have migrated, but if you're using something obscure, you might need to wait, fork it, or write your own replacement.

Plan for 1-2 weeks of work for a typical app, mostly spent debugging library compatibility. Once you're on the new arch, you'll never want to go back.