Core Web Vitals & PageSpeed Diagnostics
Inspect live performance diagnostics using official Google PageSpeed API data. Distinguishes simulated Lighthouse mobile lab diagnostics from 28-day Chrome User Experience Report (CrUX) field experience.
Understanding Lab Data vs. CrUX Field Data
Google distinguishes between Lighthouse Lab Diagnostics and CrUX Field Data per the official Google PageSpeed documentation. Lab data measures load performance in an isolated, simulated environment to reproduce and debug issues. Field data represents aggregated real-world measurements from actual Chrome users across the globe over a 28-day collection period.
Ensures primary hero text and images render immediately when the visitor arrives.
Prevents layout jumps caused by late-loading banner ads or un-dimensioned images.
Measures overall page responsiveness during clicks and taps (available from real-user CrUX data).
Frequently Asked Questions
The Chrome User Experience Report (CrUX) requires a minimum threshold of real-user visits from Chrome users who have opted into sync. New or low-traffic websites do not have enough real-world visits to generate a statistically valid 28-day 75th-percentile sample.
INP replaced First Input Delay (FID) in March 2024. Because real interactions (clicks, taps, keypresses) require actual user actions on the page, INP is primarily evaluated via CrUX field data. In lab simulations, Total Blocking Time (TBT) is used as a proxy correlate.