PageSpeed Insights

PageSpeed Insights runs Lighthouse diagnostics for a simulated test and, where sufficient observations exist, shows Chrome User Experience Report (CrUX) field data. Lab and field data answer different questions: laboratory measurements help reproduce potential bottlenecks, while field measurements summarize real visitors across conditions and devices. A page may have Lighthouse scores without enough field data for a URL-level Core Web Vitals evaluation.

The field experience view includes metrics such as Largest Contentful Paint (LCP), Interaction to Next Paint (INP) and Cumulative Layout Shift (CLS). Reports can be different for mobile and desktop. A single lab score can fluctuate because test conditions and third-party resources vary; use diagnostics to investigate causes rather than chasing a score with no user benefit.

PSI is a performance diagnostic tool, not the same thing as Google Search Console Insights or a direct report of search rankings. Improving genuinely slow experiences can benefit users, but passing a synthetic audit does not guarantee better rankings, traffic or conversions. Check live business-critical paths after each major change.