Core Web Vitals evidence guide.

What to verify

A trustworthy performance review separates 28-day real-user field data from a repeatable lab diagnosis. TechTenstein does not invent field data when an origin has too little public traffic or an API is unavailable.

1. Check origin and individual URL field data for LCP, INP and CLS.
2. Record device, location, network, date and tool version for lab runs.
3. Find the slow resource or interaction in a trace before changing code.
4. Re-run the same setup and wait for the field-data window before claiming impact.