Originally published at recca0120.github.io "React Compiler auto-memos everything — I don't need manual optimization, right?" That was me six months ago. Then a user reported tab switching was laggy.
I opened React DevTools Profiler and recorded a single commit at 512ms. Cold sweat. The project runs React 19 + React Compiler 1.0.
In theory, useMemo, useCallback, and React.memo are all automatic. I