Can useMemo and useCallback hurt React performance?
Yes. Memoization is not free, and using these hooks for cheap computations, without a memoized child, or with wrong dependencies adds overhead without benefit. The default should be no memoization, added only where measured.
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More FAQs in When useMemo and useCallback Actually Hurt React Performance
Because each useMemo and useCallback call has overhead: storing dependencies, comparing them on every render, and managing the cache. For cheap computations, this overhead exceeds the saving.
No. useCallback only helps if the child receiving the function is wrapped in React.memo. If the child is not memoized, it re-renders anyway, so the stable reference provides no benefit and the overhead is wasted.
Missing dependencies cause stale values; too many cause recomputation on every render. Wrong dependency arrays undo the memoization, so you have overhead without the benefit you expected.
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