Medium impact · weight 6 · worth up to 2.5 points of the total score
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. INP replaced First Input Delay (FID) as a Core Web Vital in March 2024.
Break up long JavaScript tasks, defer work that is not needed for the first interaction, and cut third-party scripts on the critical path.
Check a page for this, and the other 75 checks at once
HTML is compressed in transit
Gzip or Brotli typically cuts HTML to a quarter of its size. Serving it uncompressed wastes that bandwidth on every single request, and it is usually one line of server config.
Time to first byte
How long the server took to start answering, measured on our own request. A slow first byte delays everything downstream no matter how well the front end is built.
Response carries cache headers
Without a usable Cache-Control header, browsers and CDNs re-fetch the page on every visit, so returning visitors pay the full load cost again for content that did not change.
HTML document weight
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.
