performance-optimization Skill

Performance Optimization

Measure the bottleneck before optimizing it.

Workflow

1. Define the user or system target: p50/p95/p99 latency, throughput, startup, memory ceiling, frame budget, bundle size, query cost, or error budget.
2. Build a representative and repeatable workload with realistic data, concurrency, cache state, network, and device assumptions.
3. Capture a baseline with profiler, trace, query plan, browser performance panel, bundle analyzer, or resource metrics. Record variance and warm/cold state.
4. Rank bottlenecks by user impact and cost. Form one falsifiable hypothesis.
5. Make the smallest change, rerun the same workload, and compare effect and regressions. Keep only improvements that meet the target without violating correctness, accessibility, cost, or operability.
6. Add a regression budget/check where the risk is likely to recur.

Read measurement.md. Do not optimize a benchmark that does not represent the user path, hide work by weakening correctness, or claim improvement from one noisy run.

Completion condition

The bottleneck, baseline, change, before/after result, variance, trade-offs, and remaining limits are documented.