# Rerender Memo

> Extract expensive work into memoized components with React.memo. Apply when components perform expensive computations that can be skipped when props haven't changed. Use when this capability is needed.

- Skill: `tomevault-io/rerender-memo` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add tomevault-io/rerender-memo`
- Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/rerender-memo/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Web & Frontend
- Author: tomevault-io (https://skillmd.com/u/tomevault-io)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/tomevault-io/rerender-memo

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## Extract to Memoized Components

Extract expensive work into memoized components to enable early returns before computation.

**Incorrect (computes avatar even when loading):**

```tsx
function Profile({ user, loading }: Props) {
  const avatar = useMemo(() => {
    const id = computeAvatarId(user)
    return <Avatar id={id} />
  }, [user])

  if (loading) return <Skeleton />
  return <div>{avatar}</div>
}
```

**Correct (skips computation when loading):**

```tsx
const UserAvatar = memo(function UserAvatar({ user }: { user: User }) {
  const id = useMemo(() => computeAvatarId(user), [user])
  return <Avatar id={id} />
})

function Profile({ user, loading }: Props) {
  if (loading) return <Skeleton />
  return (
    <div>
      <UserAvatar user={user} />
    </div>
  )
}
```

**Note:** If your project has [React Compiler](https://react.dev/learn/react-compiler) enabled, manual memoization with `memo()` and `useMemo()` is not necessary. The compiler automatically optimizes re-renders.

---
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<!-- tomevault:4.0:skill_md:2026-04-11 -->