midReact Hooks
What is useMemo and why is it used?
Updated May 6, 2026
Short answer
useMemo memoizes expensive calculations to optimize performance.
Deep explanation
It prevents recomputation of derived values unless dependencies change, reducing unnecessary CPU work during renders.
Real-world example
Filtering large lists or performing heavy calculations in dashboards.
Common mistakes
- Using useMemo everywhere unnecessarily, causing overhead.
Follow-up questions
- Is useMemo a performance guarantee?
- Difference between useMemo and useCallback?