Slash Command28.8k repo starsupdated today

you-might-not-need-a-memo

This Claude Code slash command detects and fixes unnecessary useMemo and React.memo usage in React code by identifying seven common anti-patterns, including memoizing cheap computations, unstable dependency arrays, and cases where state relocation or component composition would be more effective. Use it when reviewing code for performance optimization opportunities to eliminate redundant memoization that adds complexity without measurable benefit.

View source Repository: sim

Install in Claude Code

Copy

mkdir -p ~/.claude/commands && curl -fsSL https://raw.githubusercontent.com/simstudioai/sim/HEAD/.claude/commands/you-might-not-need-a-memo.md -o ~/.claude/commands/you-might-not-need-a-memo.md

Then start a new Claude Code session; the slash command loads automatically.

Definition

you-might-not-need-a-memo.md

# You Might Not Need a Memo

Arguments:
- scope: what to analyze (default: your current changes). Examples: "diff to main", "PR #123", "src/components/", "whole codebase"
- fix: whether to apply fixes (default: true). Set to false to only propose changes.

User arguments: $ARGUMENTS

## References

Read before analyzing:
1. https://overreacted.io/before-you-memo/ — two techniques to avoid memo entirely

## Anti-patterns to detect

1. **State can be moved down instead of memoizing**: Move state into a smaller child so the slow component stops re-rendering without memo.
2. **Children can be lifted up**: Extract stateful part, pass expensive subtree as `children` — children as props don't re-render when parent state changes.
3. **useMemo on cheap computations**: Small array filters, string concat, arithmetic don't need memoization.
4. **useMemo with constantly-changing deps**: Deps change every render = useMemo does nothing.
5. **useMemo to stabilize props for non-memoized children**: If the child isn't wrapped in React.memo, stable references don't matter.
6. **React.memo on components that always receive new props**: Fix the parent instead.
7. **useMemo for derived state**: Just compute inline during render.

## Steps

1. Read the reference above
2. Analyze the specified scope for the anti-patterns listed above
3. If fix=true, apply the fixes. If fix=false, propose the fixes without applying.