Network bugs in React Native usually fall into a few categories: the request never leaves the device, the server rejects it, the response shape is different from what the app expects, or the UI keeps using stale data. The fastest way to debug them is to inspect the request, log safely, reproduce on the platform that fails, and verify the server-side trace.
Older Android phones expose every expensive choice in a React Native app: heavy startup work, oversized images, slow lists, chatty network calls, JS-thread animations, and debug-only assumptions. The goal is not to chase one magic setting. The goal is to measure on real hardware, reduce work on the critical path, and ship a release build that keeps memory, CPU, and frame time under control.
React Native upgrades are safest when you treat them as a controlled migration, not a package bump. The work spans JavaScript dependencies, native iOS and Android project files, Expo modules, build tooling, runtime versions, and QA. This guide gives you an evergreen upgrade path that works for bare React Native apps, Expo apps, and production templates.
Most production React Native apps talk to at least one REST API: auth, profiles, feeds, search, orders, payments, media, notifications, analytics, or admin workflows. The important decision is not whether you use Fetch or Axios. The important decision is whether every request goes through a typed, observable, cancellable, and secure API layer.
Memory leaks in React Native usually come from resources that outlive the screen that created them: timers, subscriptions, unresolved requests, sockets, navigation listeners, heavy lists, image caches, and native module handles. The fix is not a single package. It is a repeatable loop: reproduce the leak, profile it in a realistic build, remove the retained reference, and verify that memory returns to a stable baseline.
FlatList is fast when each row is cheap, keys are stable, virtualization is tuned for the screen, and the data layer avoids unnecessary re-renders. It becomes slow when rows contain heavy images, anonymous render functions, unstable item references, eager API calls, and too many mounted views. This guide focuses on practical fixes you can apply to production feeds, chats, catalogs, and marketplace screens.
Continuous integration for React Native should do more than run npm test.
A useful pipeline protects every pull request, builds signed release artifacts
from clean commits, keeps secrets out of the repository, and makes app store
submission repeatable.