What’s up in React Native Performance in 2024

Kadi Kraman says performance challenges include platform constraints, development speed, and how developers use tools such as useMemo and useCallback. Maciej Jastrzębski and Łukasz Łudziński caution that adding memoization everywhere may not help and can add unnecessary work. The Callstack team describes measuring metrics such as frame rate or screen loading time, then temporarily removing a component to estimate its maximum impact before choosing what to optimize.

The 2024 Ultimate Guide to React Native Optimization describes a DMAIC process: define the issue, measure it, analyze likely causes, implement a fix, and control the result over time. The yearly guide updates recommendations as libraries and tools change, and gathers material that is otherwise scattered across articles. Kraman contributed material on Expo Application Services and DevTools plugins.

Kraman says Expo Image supports both React Native and web, works with the new architecture, and serves as a reusable primitive in Expo libraries such as Camera. She notes that it does not match every FastImage feature, including header-based caching. Jastrzębski highlights FlashList as an alternative to FlatList and VisionCamera as examples of community libraries built with performance in mind.

The guests say major production apps use React Native, and that shared skills and code can reduce the time and cost of supporting iOS, Android, and web. React Native still uses platform-specific native components and allows teams to add native code when needed. Kraman also recommends using platform features so apps feel appropriate on each system.

Jastrzębski is looking forward to Static Hermes, which could speed up selected JavaScript functions through static compilation. Kraman points to Metro improvements in startup, build speed, and bundle splitting, as well as its potential for native and web apps. She says Expo uses Expo Router on the web for its blog to test and improve the tooling.