What do Core Web Vitals measure?
Core Web Vitals describe loading, responsiveness and visual stability. LCP measures when the largest content element appears, INP measures interaction responsiveness, and CLS measures unexpected layout shifts. INP replaced the earlier FID metric.
Thresholds for a good result
The targets are LCP ≤ 2.5 s, INP ≤ 200 ms and CLS ≤ 0.1. CLS is a unitless score, not a duration. Assessment requires all three targets at the 75th percentile, with mobile and desktop evaluated separately.
Field data and laboratory tests
Field data represents real visitors, devices and connections. Laboratory tests help reproduce and diagnose issues in controlled conditions. A high score in one test does not establish a good experience for real users.
How we improve the metrics
For LCP, we investigate server response, the main image and render-blocking resources. For INP, we reduce long main-thread tasks and improve event handling. For CLS, we reserve media dimensions, stabilize font rendering and avoid inserting elements that move existing content.
SEO and conversions
Good performance supports usability but does not replace useful content, relevance or credibility. We do not promise higher rankings or sales from metrics alone. We also evaluate conversions and completion of important user tasks.
Our approach at PAR HOUSE Agency
We begin with templates and actual user journeys. We remove unnecessary scripts, optimize media, fonts, caching and custom code, then verify the effects after deployment. We aim for a consistently usable experience on ordinary mobile devices rather than a single impressive test score.
