5 Crucial Changes in React Native 0.84 That Boost Performance and Simplify Your Workflow

React Native 0.84 is here, and it's packed with improvements that make your apps faster and your development smoother. With Hermes V1 as the default JavaScript engine, precompiled iOS binaries out of the box, and the removal of legacy architecture, this release focuses on performance and simplicity. Here are five key upgrades you need to know about to get the most out of React Native 0.84.

1. Hermes V1 Becomes the Default JavaScript Engine

Hermes V1 is now automatically used on both iOS and Android, replacing the previous stable Hermes version. This new engine brings significant improvements to the compiler and VM, resulting in faster execution and lower memory usage. If you're already on Hermes (default since 0.70), you'll get these benefits without any configuration changes—no migration required. For those who need to stick with the legacy Hermes, you can opt out by overriding the hermes-compiler package in your package.json, setting RCT_HERMES_V1_ENABLED=0 on iOS, or adding hermesV1Enabled=false in gradle.properties on Android. See item 5 for detailed opt-out instructions.

5 Crucial Changes in React Native 0.84 That Boost Performance and Simplify Your Workflow

2. Precompiled iOS Binaries Shipped by Default

Previously an opt-in feature, precompiled iOS binaries are now enabled out of the box. This means you no longer need to compile React Native core from source during clean builds—the .xcframework binaries are downloaded automatically during pod install. The result: significantly reduced build times. If you need to build from source (for example, to opt out of Hermes V1), simply set RCT_USE_PREBUILT_RNCORE=0 when installing pods. This change makes your daily development faster without any extra effort.

3. Legacy Architecture Code Removed by Default

Following the complete switch to the New Architecture in 0.82, React Native 0.84 continues to strip out legacy code. On iOS, the experimental RCT_REMOVE_LEGACY_ARCH flag is now default, so legacy architecture code is no longer compiled into your builds. This reduces both build time and app size. No breakages are expected if you're already on the New Architecture. The same cleanup is happening on Android, making the codebase leaner and more maintainable across the board.

4. Node.js 22 Becomes the Minimum Requirement

To take advantage of the latest performance and security features, React Native 0.84 sets Node.js 22 as the minimum version. Make sure your development environment is updated to avoid compatibility issues. If you're using an older version, upgrade now to ensure smooth operations with the new React Native toolchain. This change aligns with modern JavaScript standards and helps the framework stay performant and secure.

5. Simple Opt-Out and Customization Options

While Hermes V1 and precompiled binaries are the new defaults, React Native 0.84 provides clear ways to customize your setup if needed. To opt out of Hermes V1, use package manager overrides (e.g., "overrides": { "hermes-compiler": "0.15.0" } in npm), or set environment variables (RCT_HERMES_V1_ENABLED=0 and RCT_USE_PREBUILT_RNCORE=0 on iOS, hermesV1Enabled=false in gradle.properties on Android). For building from source, disable precompiled binaries with RCT_USE_PREBUILT_RNCORE=0. These options let you fine-tune your environment without sacrificing the benefits of the new defaults.

React Native 0.84 is a major step forward in performance and developer experience. With Hermes V1, faster builds, and a cleaner architecture, your apps will run better and your workflow will be more efficient. Upgrade today and enjoy the improvements.

5 Crucial Changes in React Native 0.84 That Boost Performance and Simplify Your Workflow

1. Hermes V1 Becomes the Default JavaScript Engine

2. Precompiled iOS Binaries Shipped by Default

3. Legacy Architecture Code Removed by Default

4. Node.js 22 Becomes the Minimum Requirement

5. Simple Opt-Out and Customization Options

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