What problem does it solve? Slow applications, regressions, and wasted optimization effort: teams often guess at bottlenecks, apply fixes that don't help, and keep changes that never paid for themselves. This Skill enforces a measure-first workflow so every optimization targets a proven bottleneck and survives only if re-measurement confirms it. ## Core Features & Use Cases - Measure-Identify-Fix-Verify-Guard Workflow: Establish baselines with synthetic tools (Lighthouse, DevTools) and RUM data (web-vitals, CrUX), then verify fixes against run-to-run variance before keeping them. - Anti-Pattern Fixes: Concrete remedies for N+1 queries, unbounded fetching, connection pool exhaustion, missing image optimization, unnecessary React re-renders, large bundles, and misused caching. - Core Web Vitals Targets: Threshold tables for LCP, INP, and CLS plus performance budgets enforceable in CI via bundlesize and Lighthouse CI. - Use Case: An API endpoint is slow. Instead of guessing, you check the query log, find an N+1 pattern, replace it with a single include query, re-measure under identical conditions, and add a p95 latency budget to CI to guard against regression. ## Quick Start Ask the agent to profile the slow page or endpoint, identify the actual bottleneck, and propose a measured fix with before-and-after numbers.
