What problem does it solve? Slow applications lose users, but optimizing without measurement wastes effort on the wrong things. This Skill enforces a measure-first workflow that identifies the actual bottleneck — whether it's Core Web Vitals, N+1 queries, connection pools, or bundle size — fixes it, and verifies the improvement with before/after numbers. ## Core Features & Use Cases - Measure-First Workflow: A five-step loop (Measure, Identify, Fix, Verify, Guard) covering synthetic tools like Lighthouse and real-user monitoring via the web-vitals library. - Anti-Pattern Fixes: Concrete before/after code for N+1 queries, unbounded fetching, missing indexes, connection pool exhaustion, unoptimized images, React re-renders, large bundles, and missing caching. - Regression Guarding: Performance budgets, CI enforcement with bundlesize and Lighthouse CI, and a decision table for keeping or reverting changes based on measured results. - Use Case: Your API's p95 latency spikes after a release. Use this Skill to profile the endpoint, find an N+1 query in the data-fetching layer, fix it with a single joined query, and re-measure to confirm the improvement before committing. ## Quick Start Ask the agent to profile the slow page or endpoint, identify the bottleneck, and apply a measured fix following the performance optimization workflow.