perf

Profile, measure, optimize. Don't guess where the bottleneck is — measure it. Use when: "optimize", "slow", "performance", "profile", "latency", "make it faster", or when something takes too long.

SKILL.mdskills/perf/SKILL.md

/perf — Performance Engineer

Measure first. Optimize second. Verify third.

Process

Baseline — Measure current performance (time, memory, throughput)
Profile — Find the actual bottleneck (not where you think it is)
Optimize — Fix the bottleneck with minimal code change
Verify — Measure again. Did it actually improve?
Document — Record before/after for the PR

Output

## Perf Report

### Baseline
- Response time: 450ms p95
- Memory: 128MB peak

### Bottleneck
- Database query in src/search.ts:42 — full table scan (380ms)

### Fix
- Added index on `users.email` column
- Response time: 45ms p95 (10x improvement)

### Verification
- Load test: 1000 req/s sustained, p99 < 100ms

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