Guide / performance
Core Web Vitals are stories about waiting.
LCP describes when the main content appears, INP how quickly interactions respond, and CLS whether the page jumps while loading.
Fix the bottleneck you can explain
Improve LCP by prioritizing the main image or text, reducing server delay and avoiding render-blocking work. Improve INP by breaking up long JavaScript tasks and keeping event handlers small. Improve CLS by reserving space for images, embeds and late UI.
Field data beats a single laptop
Lab tests are repeatable, but real-user data captures devices, networks and input patterns. Segment by template and device before choosing a fix. A green aggregate can hide a painful mobile experience.
Diagnostic habit: write the user-visible symptom beside the metric. “The headline appears late” leads to better work than “LCP is 4.2s.”
Also check HTTP status codes; a fast error page is not a healthy page.