Metrics evaluating loading performance, responsiveness, and visual stability: LCP, INP, and CLS.
Core Web Vitals are a small set of measurements describing different aspects of page experience. Largest Contentful Paint covers loading, Interaction to Next Paint covers responsiveness and Cumulative Layout Shift covers visual stability. They help make complaints such as “the page feels slow” more specific instead of treating every performance problem as one issue.
The recommended good thresholds are LCP at or below 2.5 seconds, INP at or below 200 milliseconds and CLS at or below 0.1. Assessments use the 75th percentile of measured experiences, with mobile and desktop considered separately. A single fast test on your own computer does not establish that real visitors meet all three thresholds.
These measurements are not a complete evaluation of a website. A page can have strong scores while containing outdated information or a broken booking link. Google uses Core Web Vitals in its ranking systems, but good scores do not guarantee high rankings. Treat them as evidence about user experience rather than a substitute for relevance or useful content.
Takeaway: Identify which measurement is poor and which pages or visitors are affected before buying a speed fix. Verify that the improvement helps the actual experience, not just one test result.
Example
A garden center’s product pages load their main photos promptly but jump when a promotion banner appears. That is primarily a stability problem, not evidence that every image needs further compression. The team first investigates the shifting layout while continuing to check that stock information and purchase controls remain usable.
What to check
Check whether a report shows real-user field data, a controlled lab test or both. Keep the device category and measurement period attached to any result you share with a developer.
For more detail, see Web.dev Core Web Vitals.