Three metrics, three useful questions
Google’s Web Vitals guidance defines good thresholds of LCP at 2.5 seconds or less, INP at 200 milliseconds or less, and CLS at 0.1 or less, evaluated at the 75th percentile and separated for mobile and desktop. Treat these as defined reference thresholds, not measured results for this site.
Loading / LCP
When does the main content become available? Inspect the document, relevant visual, and the work that happens before the content can appear.
Interaction / INP
How does the interface respond to meaningful actions? Test the menu, disclosure, filter, or control the visitor actually needs.
Stability / CLS
Does unexpected movement interrupt reading or navigation? Observe the layout while content arrives, not only after it is settled.
Give lab and field evidence different jobs
A controlled test can help you investigate a reproducible scenario. A field report describes a measured population and time window. Record those contexts explicitly rather than expecting their values to be identical.
Choose one page family, write the task, and change one plausible cause where practical. Verify the release and the functional experience before interpreting the later reporting window.
A practical Web Vitals workflow
Move from definitions to a prioritised, testable performance investigation.
Read the performance guideLab tests and measured visits
Keep the page, conditions, population, and time boundary visible.
Compare the approaches