Start with field impact
When eligible field data exists, use it to understand real-user experience. Use the lab run to reproduce bottlenecks and test a concrete change.
Google provider evidence · Lighthouse + field data
Measure page performance without mixing lab and real-user data
Run Google PageSpeed Insights for mobile or desktop. Review Lighthouse categories, lab timings, optimization opportunities, failed automated audits, and separately labeled page or origin field experience when Google returns it.
LAB SOURCELIGHTHOUSEFIELD SOURCEGOOGLE PSICREDENTIALOPTIONAL + USE ONCE
PSI
Ready for a public page.
No sample score, estimated Core Web Vitals, or generated opportunity is displayed. Results begin with Google’s live provider response.
Performance practice
Measure, change one constraint, then measure again
Compare the same strategy
Mobile and desktop use different environments. Keep the URL, strategy, release state, and timestamp attached before comparing two runs.
Inspect the actual audit
Estimated savings are guidance from one model. Confirm network, cache, rendering, accessibility, and SEO behavior with the appropriate evidence source.
PageSpeed API methodGoogle PageSpeed API guideChrome UX Report API