Performance Optimizer
Analyze and suggest performance improvements for code, queries, or systems.
Purpose
Identify optimization opportunities:
- Runtime performance bottlenecks
- Memory usage issues
- Database query inefficiencies
- Bundle size problems
- Algorithm complexity
Instructions
Step 1: Scope Identification
Determine optimization target:
- Function: Single function performance
- Module: Related functions/classes
- Query: Database query optimization
- Bundle: Frontend bundle analysis
- System: Architecture-level optimization
Step 2: Performance Analysis
Runtime Analysis
bash# Find potentially slow patterns grep -rn "forEach\|\.map\|\.filter\|\.reduce" --include="*.{ts,js}" . | head -20 # Find nested loops (O(n²) potential) grep -rn "for.*for\|\.forEach.*\.forEach\|\.map.*\.map" --include="*.{ts,js}" . | head -10 # Find sync operations that could be async grep -rn "readFileSync\|writeFileSync\|execSync" --include="*.{ts,js}" . | head -10
Memory Analysis
bash# Large array operations grep -rn "new Array\|Array\.from\|\.concat\|spread" --include="*.{ts,js}" . | head -10 # Potential memory leaks (event listeners, intervals) grep -rn "addEventListener\|setInterval\|setTimeout" --include="*.{ts,js}" . | head -10
Database Query Analysis
bash# N+1 query patterns grep -rn "await.*find\|await.*query" --include="*.{ts,js}" . | head -15 # Missing indexes hints grep -rn "WHERE\|ORDER BY\|GROUP BY" --include="*.{ts,js,sql}" . | head -15
Bundle Analysis
bash# Check bundle size (if applicable) [ -f "package.json" ] && npm run build 2>/dev/null && ls -lh dist/*.js 2>/dev/null # Large dependencies [ -f "package.json" ] && cat package.json | jq '.dependencies | keys[]' | head -20
Step 3: Prioritization
Rank findings by:
- Impact: How much will this improve performance?
- Effort: How hard is the fix?
- Risk: What could break?
Output Format
⚡ Performance Analysis
Target: [file/module/system] Analysis Date: [timestamp]
📊 Current Metrics (if measurable)
| Metric | Current | Target | Gap |
|---|---|---|---|
| Response time | Xms | <Yms | -Z% needed |
| Memory usage | XMB | <YMB | -Z% needed |
| Bundle size | XKB | <YKB | -Z% needed |
🔴 Critical Issues
1. [Issue Title] - [Location]
Problem: [What's slow and why]
Current:
typescript// O(n²) - nested loops users.forEach(user => { permissions.forEach(perm => { if (user.id === perm.userId) { ... } }); });
Optimized:
typescript// O(n) - Map lookup const permMap = new Map(permissions.map(p => [p.userId, p])); users.forEach(user => { const perm = permMap.get(user.id); if (perm) { ... } });
Impact: ~10x faster for 1000 users Effort: Low (5 min) Risk: Low
🟠 High Priority
| Issue | Location | Impact | Effort |
|---|---|---|---|
| [description] | file:line | [estimate] | [time] |
🟡 Medium Priority
| Issue | Location | Impact | Effort |
|---|---|---|---|
| [description] | file:line | [estimate] | [time] |
💡 Quick Wins
- [Small change with good impact]
- [Another quick optimization]
- [Low-hanging fruit]
📈 Optimization Roadmap
Week 1: Critical fixes (items 1-3) Week 2: High priority (items 4-6) Week 3: Measure and validate improvements
Common Patterns
Array Operations
| Pattern | Issue | Fix |
|---|---|---|
arr.filter().map() | Two iterations | Single reduce() or flatMap() |
arr.find() in loop | O(n²) | Build Map/Set first |
[...arr1, ...arr2] | Memory allocation | arr1.concat(arr2) or push |
Database
| Pattern | Issue | Fix |
|---|---|---|
| Loop with await | N+1 queries | Batch query with IN |
SELECT * | Over-fetching | Select only needed columns |
| Missing WHERE index | Full table scan | Add composite index |
React/Frontend
| Pattern | Issue | Fix |
|---|---|---|
| Inline functions in JSX | Re-renders | useCallback |
| Large list rendering | DOM thrashing | Virtualization |
| Unoptimized images | Slow LCP | Next/Image, lazy loading |
Node.js
| Pattern | Issue | Fix |
|---|---|---|
| Sync file operations | Blocks event loop | Async alternatives |
| JSON.parse large files | Memory spike | Streaming parser |
| No connection pooling | Connection overhead | Pool with pg-pool, etc. |
Usage
Analyze specific file:
/optimize src/services/user.ts
Focus on specific area:
/optimize --queries src/repositories/ /optimize --bundle /optimize --memory src/workers/
With target metrics:
/optimize --target=100ms src/api/search.ts
Quick scan:
/optimize --quick
Notes
- Measurements beat assumptions: profile before optimizing
- Premature optimization is the root of all evil (Knuth)
- Focus on hot paths: optimize what runs often
- Consider trade-offs: speed vs readability vs maintainability
$ARGUMENTS
