Performance & Core Web Vitals
Performance is a user-experience concern first and a Google Search ranking signal second — slow pages lose users, and Google's page experience signals factor Core Web Vitals (CWV) into ranking. This page is the performance-testing pillar that complements Testing Strategy: it covers what Lighthouse measures, what the Core Web Vitals are and how they're scored, the difference between lab and field data, how to actually run audits (DevTools, CLI, PageSpeed Insights, Lighthouse CI, RUM), and a recommended Aliz workflow. Per-metric optimisation guidance stays as short checklists with links out to web.dev — no need to duplicate what's already well-documented there.