The three measures
Largest Contentful Paint (LCP) is how long the main content takes to appear. Google considers 2.5 seconds or less good. Interaction to Next Paint (INP) is how quickly the page responds when someone taps; 200 milliseconds or less is considered good. Cumulative Layout Shift (CLS) is how much things jump around while loading; 0.1 or less is good. Check Google's current thresholds.
How to check
Run your page through PageSpeed Insights. It shows lab tests and, when enough data exists, real-user data. The Core Web Vitals report in Search Console groups your pages.
Common causes of slow pages
Oversized images. Fonts and CSS that block rendering. Too many scripts from plug-ins, chat widgets and trackers. Slow hosting without caching or compression.
Common fixes
Compress and resize images, using modern formats. Load fonts efficiently. Defer scripts you do not need immediately. Turn on caching and compression. Set image sizes so the page does not jump.
Keep it in perspective
Speed matters mostly because visitors leave slow sites. A good score will not outrank better content, but a bad one can cost you customers.
Common questions
Do I need a perfect score?
No. Aim for a fast real-world experience on a phone.
Why does my score change each time?
Lab tests vary with network and server conditions. Look at trends and real-user data.
This guide is general information. Search engines change how they work and their guidelines; check Google's current documentation for your situation. Nobody can guarantee a ranking.