The Facebook team recently announced their newest React Native version, which comes with some huge improvements. While some of these changes are focused on the developer experience, the main ones will benefit all users of these apps.
In a direct comparison done by the engineering team at Facebook of a React Native app leveraging Hermes versus another without the Hermes engine, we identified 3 key improvements we see having an immediate impact on app performance:
With all of the improvements mentioned above for apps running Hermes, some apps were unable to use Hermes due to compatibility issues with popular libraries (for example react-native-firebase and mobx). Proxy support has now been added to Hermes in this version to allow those apps to enable Hermes and get all of the performance benefits that come with it.
Previously, being able to do an in-depth analysis of the performance of your application took additional plugins or libraries. Now, developers running React Native using Hermes can easily check these details in the Performance tab of Chrome DevTools to ensure the app is always running at the high speeds we expect. This also allows developers to more easily debug any performance issues and isolate areas of the app that might need some more optimization.
According to the React Native release blog:
While this feature has been available for use for a couple years, it is now enabled by default.