performance-profiler — Claude Code subagent: profile and optimize

What performance-profiler does

The subagent covers several areas at once: response times and throughput, memory leaks and garbage collection, CPU load, API latency, database queries and frontend metrics like bundle size. It starts by capturing a baseline, then compares later runs against it.

Bundled Node.js profiling scripts rely on perf_hooks, v8-profiler-next and @airbnb/node-memwatch, so those packages need to be present in your project. Reports land in ./performance-reports: a CPU profile as .cpuprofile and a heap snapshot as .heapsnapshot. There is also event loop delay monitoring that warns when the mean delay goes above 10 ms.

The agent is meant to be invoked proactively, stepping in whenever a task touches performance. Its toolset is limited to reading, writing, editing files and Bash, so it will not wire up an external APM service for you. CPU analysis works on a profile the script has already saved, so nothing gets reviewed until the profiler actually runs against your app.