Performance Review

When reviewing code for performance issues, check each category below. Reference the detailed checklist in references/performance-checklist.md.

Database & Queries

• •N+1 query patterns (queries inside loops)
• •Missing database indexes for frequently queried fields
• •Unbounded queries without LIMIT/pagination
• •SELECT * instead of selecting only needed columns
• •Missing connection pooling

Memory & Resources

• •Memory leaks: event listeners not removed, intervals not cleared, growing caches without bounds
• •Large objects held in memory unnecessarily
• •Unbounded arrays or maps that grow with usage
• •Missing cleanup in component unmount/destroy lifecycle

Rendering (Frontend)

• •Unnecessary re-renders (missing React.memo, useMemo, useCallback where appropriate)
• •Large component trees re-rendering for small state changes
• •Missing virtualization for long lists
• •Synchronous heavy computation blocking the main thread
• •Large bundle sizes from unnecessary imports

API & Network

• •Missing caching for frequently accessed, rarely changing data
• •Sequential API calls that could be parallelized
• •Missing pagination for large data sets
• •Over-fetching data (requesting more than needed)
• •Missing request deduplication

Algorithmic Complexity

• •O(n²) or worse operations on potentially large datasets
• •Repeated computation that could be memoized
• •String concatenation in loops (use array join or template literals)
• •Unnecessary sorting or filtering passes

Severity Levels

• •🔴 CRITICAL: Will cause performance degradation under normal load
• •🟠 HIGH: Will cause issues at scale
• •🟡 MEDIUM: Optimization opportunity with measurable impact
• •🔵 LOW: Minor optimization suggestion