name: performance-review description: Analyze React/Next.js performance issues, N+1 queries, bundle size, and Core Web Vitals. Use when optimizing components, checking for slow renders, reviewing data fetching patterns, or when the app feels sluggish.

Performance Review

Analyze code for performance issues targeting Core Web Vitals (LCP < 2.5s, FID < 100ms, CLS < 0.1).

Scope

Review the specified files or components for:

1. React/Next.js Performance

• Unnecessary client components (should be server components)
• Missing React.memo(), useMemo(), useCallback() where beneficial
• Large component re-renders (check dependency arrays)
• Missing Suspense boundaries for async components
• Heavy components that should use next/dynamic
• Improper use of use client directive

2. Data Fetching

• N+1 query patterns in Drizzle queries
• Missing Promise.all() for parallel fetches
• Overfetching data (selecting unused columns)
• Missing React cache() for request deduplication
• Unnecessary waterfalls in data loading
• Missing or improper TanStack Query configuration

3. Bundle Size

• Large dependencies imported synchronously
• Missing code splitting opportunities
• Importing entire libraries vs. specific modules
• Dead code that should be removed

4. Database Performance

• Missing indexes on filtered/joined columns
• Inefficient query patterns
• Large result sets without pagination
• Missing connection pooling considerations

5. Rendering Performance

• Layout thrashing (reading then writing DOM)
• Missing virtualization for long lists (TanStack Virtual)
• Large images without optimization
• Missing loading="lazy" on images
• CSS that causes reflows

6. Caching

• Missing cache headers on API routes
• Opportunities for static generation
• Missing revalidation strategies
• Inefficient cache invalidation

Output Format

For each finding:

[IMPACT: HIGH|MEDIUM|LOW]
File: path/to/file.ts:lineNumber
Issue: Brief description
Current: What's happening now
Recommended: How to optimize
Estimated Impact: Expected improvement

Actions

1. Analyze component render patterns
2. Review Drizzle queries for N+1 patterns
3. Check for proper server/client component split
4. Identify parallelization opportunities
5. Review image and asset loading

Post-Review

Generate a summary with:

• Quick wins (low effort, high impact)
• Medium-term optimizations
• Architectural improvements for long-term