perf-check

Analyze $ARGUMENTS for performance issues.

Check Categories

Database & Queries

• N+1 query patterns (loop with query inside)
• Missing indexes on frequently queried columns
• SELECT * instead of specific columns
• Missing pagination on list endpoints
• Unoptimized joins or subqueries

Memory & Resources

• Unclosed connections, streams, file handles
• Growing arrays/maps without limits
• Event listeners not removed on cleanup
• Large objects held in memory unnecessarily
• Missing cleanup in useEffect (React)

Frontend Performance

• Unnecessary re-renders (missing useMemo, useCallback, React.memo)
• Large bundle imports (import entire library vs specific module)
• Images without lazy loading or optimization
• Missing code splitting
• Synchronous operations blocking UI thread
• Missing virtualization for long lists

API & Network

• Missing caching (Redis, in-memory, HTTP cache headers)
• Redundant API calls
• Missing request deduplication
• Large payloads without compression
• Missing connection pooling

General

• O(n²) or worse algorithms where O(n) is possible
• Synchronous file I/O in async context
• Regex backtracking (catastrophic regex)
• Unnecessary deep cloning

Output Format

## Performance Report: [target]

### Critical (fix now)
- [file:line] [issue] [impact] [fix]

### Warning (should fix)
- [file:line] [issue] [impact] [fix]

### Suggestion (optimization)
- [file:line] [issue] [impact] [fix]

### Good Patterns Found
- [what's already well-optimized]