React • Performance • Tech

React Compiler: Goodbye useMemo?

React 19's optimizing compiler promises to automate memoization. I tested it on a large codebase to see if manual optimization is truly dead.

2/10/20258 min read

The promise of 'React Forget'

We've spent years fighting re-renders with `useMemo` and `useCallback`. The React Compiler automates this by analyzing data flow during the build step. If a value doesn't change, the component doesn't re-render. It sounds magical, but does it work in practice?

Field report

I migrated a heavy dashboard with 50+ charts. I removed all `useMemo` hooks. The result? A 15% reduction in code volume and indentical—sometimes better—performance metrics. The compiler is smart enough to memoize not just at the component boundary, but at the hook level.

▹No more dependency array management
▹Cleaner, more readable component bodies
▹Setup is trivial in Next.js 15+

Gotchas

It's not bulletproof. If you have side-effects in your render phase (which you shouldn't anyway), the compiler might aggressive optimize them away. Strict Mode compliance is now mandatory.