Speed Monitoring Skill

Purpose

Provides patterns for continuous performance monitoring to prevent speed regressions and maintain Core Web Vitals scores. Establishes automated testing, real user monitoring, and alerting systems to catch performance issues before they impact users.

Core Rules

1. Budget before build — Set performance budgets upfront in budget.json
2. Monitor real users — Lab data ≠ field data, track both synthetic and RUM
3. Alert on regression — Catch issues before users do with threshold-based alerts
4. Block bad deploys — CI fails on performance regression via Lighthouse CI
5. Track over time — Trends matter more than snapshots, store historical data
6. Measure Core Web Vitals — LCP, CLS, INP, FCP, TTFB in production
7. Automated testing — Lighthouse CI on every PR and main branch push
8. Bundle size limits — Enforce JS/CSS budgets in CI pipeline
9. Real user data — Use web-vitals library + beacon API for field data
10. Dashboard visibility — Make performance metrics accessible to team