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name: Optimizing Performance description: Optimize performance with profiling, caching strategies, database query optimization, and bottleneck analysis. Use when improving response times, implementing caching layers, or scaling for high load.

Optimizing Performance

I help you identify and fix performance bottlenecks using language-specific profiling tools, optimization patterns, and best practices.

When to Use Me

Performance analysis:

• "Profile this code for bottlenecks"
• "Analyze performance issues"
• "Why is this slow?"

Optimization:

• "Optimize database queries"
• "Improve response time"
• "Reduce memory usage"

Scaling:

• "Implement caching strategy"
• "Optimize for high load"
• "Scale this service"

How I Work - Progressive Loading

I load only the performance guidance relevant to your language:

Language Detection:
  "Python project" → Load @languages/PYTHON.md
  "Rust project" → Load @languages/RUST.md
  "JavaScript/Node.js" → Load @languages/JAVASCRIPT.md
  "Go project" → Load @languages/GO.md
  "Any language" → Load @languages/GENERIC.md

Don't load all files! Start with language detection, then load specific guidance.

Core Principles

1. Measure First

Never optimize without data. Profile to find actual bottlenecks, don't guess.

• Establish baseline metrics
• Profile to identify hot paths
• Focus on the 20% of code that takes 80% of time
• Measure improvements after optimization

2. Performance Budgets

Set clear targets before optimizing:

targets:
  api_response: "<200ms (p95)"
  page_load: "<2 seconds"
  database_query: "<50ms (p95)"
  cache_lookup: "<10ms"

3. Trade-offs

Balance performance vs:

• Code readability
• Maintainability
• Development time
• Memory usage

Premature optimization is the root of all evil. Optimize when:

• Profiling shows clear bottleneck
• Performance requirement not met
• User experience degraded

Quick Wins (Language-Agnostic)

Database

• Add indexes for frequently queried columns
• Implement connection pooling
• Use batch operations instead of loops
• Cache expensive query results

Caching

• Implement multi-level caching (L1: in-memory, L2: Redis, L3: database, L4: CDN)
• Define cache invalidation strategy
• Monitor cache hit rates

Network

• Enable compression for responses
• Use HTTP/2 or HTTP/3
• Implement CDN for static assets
• Configure appropriate timeouts

Language-Specific Guidance

Python

Load: @languages/PYTHON.md

Quick reference:

• Profiling: cProfile, py-spy, memory_profiler
• Patterns: Generators, async/await, list comprehensions
• Anti-patterns: String concatenation in loops, GIL contention
• Tools: pytest-benchmark, locust

Rust

Load: @languages/RUST.md

Quick reference:

• Profiling: cargo bench, flamegraph, perf
• Patterns: Zero-cost abstractions, iterator chains, preallocated collections
• Anti-patterns: Unnecessary allocations, large enum variants
• Tools: criterion, rayon, parking_lot

JavaScript/Node.js

Load: @languages/JAVASCRIPT.md

Quick reference:

• Profiling: clinic.js, 0x, Chrome DevTools
• Patterns: Event loop optimization, worker threads, streaming
• Anti-patterns: Blocking event loop, memory leaks, unnecessary re-renders
• Tools: autocannon, react-window, p-limit

Go

Load: @languages/GO.md

Quick reference:

• Profiling: pprof, go test -bench, go tool trace
• Patterns: Goroutine pools, buffered channels, sync.Pool
• Anti-patterns: Unlimited goroutines, defer in loops, lock contention
• Tools: benchstat, sync.Map, strings.Builder

Generic Patterns

Load: @languages/GENERIC.md

When to use: Database optimization, caching strategies, load balancing, monitoring - applicable to any language.

Optimization Workflow

Phase 1: Baseline

1. Define performance requirements
2. Measure current performance
3. Identify user-facing metrics (response time, throughput)

Phase 2: Profile

1. Use language-specific profiling tools
2. Identify hot paths (where time is spent)
3. Find memory bottlenecks
4. Check for resource leaks

Phase 3: Optimize

1. Focus on biggest bottleneck first
2. Apply language-specific optimizations
3. Implement caching where appropriate
4. Optimize database queries

Phase 4: Verify

1. Re-profile to measure improvements
2. Run performance regression tests
3. Monitor in production
4. Set up alerts for degradation

Common Bottlenecks

Database

• Missing indexes
• N+1 query problem
• No connection pooling
• Expensive joins → Load @languages/GENERIC.md for DB optimization

Memory

• Memory leaks
• Excessive allocations
• Large object graphs
• No pooling → Load language-specific file for memory management

Network

• No compression
• Chatty API calls
• Synchronous external calls
• No CDN → Load @languages/GENERIC.md for network optimization

Concurrency

• Lock contention
• Excessive threading/goroutines
• Blocking operations
• Poor work distribution → Load language-specific file for concurrency patterns

Success Criteria

Optimization complete when:

• ✅ Performance targets met
• ✅ No regressions in functionality
• ✅ Code remains maintainable
• ✅ Improvements verified with profiling
• ✅ Production metrics show improvement
• ✅ Alerts configured for degradation

Next Steps

• Use profiling tools to identify bottlenecks
• Load language-specific guidance
• Apply targeted optimizations
• Set up monitoring and alerts

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Load language-specific files for detailed profiling tools, optimization patterns, and best practices