When can overusing useMemo hurt performance and what are the trade-offs?
WHAT IT TESTS: Awareness that useMemo has memory and comparison overhead. ANSWER OUTLINE: Memoizing cheap work wastes cycles, increases memory use, and burdens dependency tracking. RED FLAG: Claiming useMemo is free or automatically blocks child re-renders.
WHAT IT TESTS: Your grasp of useMemo's hidden runtime and memory costs and when memoization is premature optimization. ANSWER OUTLINE: A strong answer explains that useMemo caches values and compares dependencies on every render, so wrapping cheap calculations or primitives adds pure overhead while increasing memory pressure, dependency complexity, and the risk of stale closure bugs. RED FLAG: Asserting useMemo is always free or that it automatically prevents child re-renders without React.memo.
Read the original → react.dev
- #react
- #usememo
- #performance
- #memoization
- #interview
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