Performance Analysis

Analyze code changes for performance implications and optimization opportunities.

Scope

Review changes from: !git diff --name-only HEAD~1 or files specified in $ARGUMENTS

Performance Checklist

1. Database Operations

• N+1 queries: Check for loops that execute individual queries
• Missing indexes: Verify queries use indexed columns in WHERE/JOIN clauses
• Large result sets: Check for unbounded queries without LIMIT
• Transaction scope: Verify transactions are as short as possible
• Connection pooling: Ensure proper connection handling

2. Memory Usage

• Large object allocation: Check for unnecessary large arrays/objects
• Memory leaks: Look for unclosed connections, streams, or event listeners
• Buffer handling: Verify streaming for large files instead of loading into memory
• Caching strategy: Check if frequently accessed data could be cached

3. API Performance

• Response size: Check for over-fetching data
• Compression: Verify gzip is enabled for large responses
• Pagination: Confirm list endpoints are paginated
• Async operations: Check if operations can be parallelized

4. Algorithmic Complexity

• Loop efficiency: Look for O(n^2) or worse patterns
• Data structure choice: Verify appropriate use of Map/Set vs Array
• Unnecessary iterations: Check for redundant loops over same data
• Early returns: Verify functions exit early when possible

5. Caching

• Redis usage: Check if cacheable data is being cached
• Cache invalidation: Verify cache keys are invalidated on updates
• TTL settings: Confirm appropriate expiration times
• Route caching: Check if expensive endpoints use route caching

6. Geographic/Spatial Operations

• PostGIS queries: Verify spatial indexes are used
• H3 resolution: Check appropriate H3 resolution for use case
• Geometry simplification: Confirm geometries are simplified for display

7. Deno-Specific

• Module loading: Check for dynamic imports that could be static
• Worker threads: Consider if CPU-intensive work should use workers
• Streaming: Use Deno streams for file/network operations

Metrics to Consider

Operation	Target	Warning
API response time	< 200ms	> 500ms
Database query	< 50ms	> 200ms
Memory per request	< 10MB	> 50MB
Batch size	100-1000	> 10000

Output Format

## Performance Analysis Summary

**Impact Level**: [LOW | MEDIUM | HIGH]
**Files Reviewed**: X files

### Performance Issues

#### [IMPACT] Issue Title
- **File**: path/to/file.ts:line
- **Issue**: Description of the performance problem
- **Current complexity**: O(n^2) / Memory: ~XMB / Time: ~Xms
- **Suggested improvement**: How to optimize
- **Expected improvement**: X% faster / X% less memory

### Optimization Opportunities
- Optional improvements that aren't blocking

### Approved Changes
- List of changes with acceptable performance characteristics

### Benchmarks Suggested
- [ ] Specific scenarios that should be load tested

Invocation

/check-perf                        # Review uncommitted changes
/check-perf src/pdc/services/      # Review specific directory
/check-perf --focus=database       # Focus on database operations