Low impact · weight 4 · worth up to 2.5 points of the total score
This is the HTML document alone, before images and scripts. A multi-megabyte document usually means the whole page was rendered server-side into one response, and every visitor pays for it on every load.
Paginate long lists, move repeated markup into components, and stop inlining large data blobs into the document.
Check a page for this, and the other 41 checks at once
Lighthouse performance score
Google's own composite of loading, interactivity, and visual stability, measured on a simulated mid-range phone. This is the number PageSpeed Insights puts at the top of its report.
Largest Contentful Paint
LCP is the moment the biggest element in the viewport finishes rendering, which is when a visitor feels the page has arrived. Google's threshold for good is 2.5 seconds.
Cumulative Layout Shift
CLS measures content jumping around after it appears. It is why a visitor taps the wrong button when an ad or a late-loading image pushes the page down under their finger.
Interaction to Next Paint
INP is how long the page takes to visibly respond after a tap or a click. Above 200ms the interface starts to feel like it is ignoring the user.
