Nginx C Module Perf

This is the performance counterpart to the nginx-c-modules correctness skill, focused entirely on making your C modules fast and resilient under load. You get 43 rules across buffer management, connection pooling, lock contention, error recovery, and caching strategies, all pulled from nginx.org's development guide and production experience. The priorities are sensible: zero-copy I/O and connection efficiency are marked critical, lock contention and error handling are high, and logging comes last. Use this when you're profiling a slow module, debugging worker stalls from shared memory locks, or implementing an in-module cache. The distinction between correctness and performance skills is helpful since optimization work has a different mindset than getting the request lifecycle right.