React Performance: A Rendering Checklist (Memoization, Virtualization, and Profiling)

React performance is less about one trick and more about a repeatable checklist: measure, isolate, fix, and prevent.

1) Start with profiling (not guessing)

• Use React DevTools Profiler.

• Find components re-rendering too often.

• Confirm renders cause slow frames.

2) Memoization: use it surgically

const value = useMemo(() => computeValue(data), [data]); const onClick = useCallback(() => doThing(id), [id]);