If React app performance declines, check for unnecessary re-renders, optimize component states, and use memoization. Profiling tools can help pinpoint bottlenecks.

Performance drops in a React application often stem from inefficient rendering, state management, or excessive data processing. One of the first steps in troubleshooting is to use React’s built-in profiling tools, which can reveal components that re-render excessively or take too long to render. Unnecessary re-renders often occur due to prop or state changes, so consider using React’s memo for functional components or PureComponent for class components to prevent re-renders when the props haven’t changed. Additionally, managing component states effectively is essential; lift state up to common ancestors or utilize context only for truly shared data. For instance, using a state management library like Redux or MobX can help centralize state, reducing prop drilling and making state updates more predictable and manageable. Another strategy is memoization, particularly for functions or computations that don’t need recalculating with every render. The useMemo and useCallback hooks are useful here to cache expensive calculations or functions between renders. Also, if you’re fetching data, consider whether your app is re-fetching unnecessarily. Libraries like SWR or React Query can manage data fetching and caching, ensuring that your app doesn’t perform redundant network requests. By combining these strategies—component optimization, effective state management, and memoization—you can improve and sustain your app’s performance even as new features are added.