PHP API Performance Fix

I'm looking for an experienced PHP developer to fix performance issues with an implemented API on production. The API is currently experiencing inconsistent performance, particularly when specific requests are made.

Key Requirements:
- Diagnose and resolve performance bottlenecks
- Optimize existing code and database queries
- Ensure stable and consistent API performance

Ideal Skills and Experience:
- Strong expertise in PHP and API development
- Experience with performance tuning and optimization
- Familiarity with production environments and debugging

Please provide examples of similar work done and your approach to resolving such issues.