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For ordinary callback memoization in new React code, you usually do not need to add useCallback everywhere: React recommends relying on React Compiler to infer memoization. Keep useCallback when you need precise control over a stable function identity, and do not remove existing calls across a codebase without testing. The compiler is a build-time optimizer, not a promise that every function will be cached.
How React Compiler changes callback memoization
React Compiler analyzes components and hooks at build time and can add memoization automatically. For new code, the React team recommends relying on that analysis for ordinary memoization, using useMemo or useCallback when precise control is needed. This reduces manual bookkeeping; it is not a claim that every callback is optimized or that a particular app will become faster by a measurable amount. React’s October 7, 2025 announcement of React Compiler 1.0 describes the recommendation.
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The benefit is especially clear when manually stabilizing one function does not stabilize the function actually passed to a child. React’s introduction shows a handleClick wrapped in useCallback, then passed to list items through an inline arrow function such as () => handleClick(item). That arrow is newly created on each render. The compiler can optimize this pattern without requiring you to manually stabilize every layer. React’s compiler introduction presents it as an example, not a benchmark.
When keeping useCallback makes sense
useCallback remains available when you want explicit control over a function’s identity. One documented use is keeping a function stable when it is a dependency of an Effect, so the Effect does not rerun merely because a new function was created during rendering. React describes the hook as a performance optimization, however, and its cached value may be discarded in certain circumstances. Correctness should not depend on that cache being permanent. See the useCallback API reference.
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- Keep it when you have a specific need for a stable function identity, such as an Effect dependency.
- Do not add it reflexively to every event handler in new code.
- Measure or inspect the actual behavior before introducing memoization solely in pursuit of a presumed performance gain.
Should you remove existing useCallback calls?
Not all at once. React advises leaving existing manual memoization in place or carefully testing before removing it, because manual memoization can affect the compiler’s output. A cleanup that deletes every useCallback call may change which code is compiled or how it behaves.
Review calls individually: determine whether a stable identity is needed, confirm the affected components are eligible for compilation, and test the changed behavior. React’s compiler introduction discusses the interaction with existing memoization.
What the compiler does—and does not—optimize
The compiler primarily targets component update performance. It can skip cascading rerenders and memoize some expensive calculations within components and hooks. It does not memoize every ordinary JavaScript function, and a calculated value is not automatically shared as a cache across separate components or hooks. If expensive work is shared across components, profile the application and choose a suitable strategy rather than assuming compiler memoization will provide a shared cache. React’s introduction outlines these boundaries.
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React announced React Compiler 1.0 as stable on October 7, 2025, calling it production-ready and noting its use at Meta. Stable does not mean every application should enable it everywhere without checking its code. React’s guidance ties successful adoption to following the Rules of React and the health of the codebase. The release announcement and introduction describe both points.
The installation guide lists React 17, 18, and 19 as supported, with React 19 the best fit, and documents the Babel plugin plus integrations for Babel, Vite, Metro, and Rsbuild. React’s introduction also identifies Next.js 15.3.1 and later as supporting the compiler through SWC. These framework and toolchain details can change, so check the current guide for your setup.
- Start with a small area. Follow React’s incremental adoption guidance and verify behavior and performance before expanding.
- Use controlled compilation where appropriate. Annotation mode can compile functions marked with
"use memo"; runtime gating can support a controlled rollout. The installation and adoption guides explain the available options. - Inspect compiler coverage. After setup, React DevTools can show a “Memo ✨” badge for compiled components. See the installation guide.
- Exclude a problem area temporarily if needed. React documents
"use no memo"as a way to exclude a component while investigating an issue. See the incremental adoption guide.
What to test before expanding adoption
Do not make application correctness depend on referential equality or on a memoized reference persisting forever. Changes to memoization can affect code that relies on stable references in Effect dependency arrays; React warns that problems can range from Effects firing too often to loops or missed updates. Check the relevant dependency behavior and exercise important flows with end-to-end tests when adopting or upgrading the compiler. React’s troubleshooting guidance covers these risks.
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