Guides
Every guide is complete on its own — the full fix, with real code, whether or not you buy anything. The diagrams are free to reuse. Not sure which problem you have? Run the check and it will point you at the right one.
Fixing a specific problem
Slow LCPHow to fix a slow LCPYour main image or headline takes too long to appear.Layout shiftHow to fix layout shiftContent jumps around while the page loads.Sluggish interactionHow to fix slow INPTaps and clicks take a moment to do anything.Server latencyHow to fix a slow server responseYour server is slow to start replying at all.Blocking assetsHow to eliminate render-blocking CSS and JSCSS and JS files stop anything appearing on screen.Oversized imagesHow to fix oversized and outdated imagesYour images weigh far more than they need to.Unused JavaScriptHow to cut unused JavaScriptYou ship JavaScript this page never runs.Cache headersHow to fix your cache headersReturning visitors re-download files they already have.
Understanding the numbers
Missing CrUX dataWhy you're seeing "no field data"Google has no real-visitor data for your site yet.Score varianceWhy your score is different on every runThe score is different every time you test.Mobile gapFast on desktop, slow on mobileDesktop looks fine; the phone test says otherwise.Search Console lagWhy Search Console still shows the old numbersYou fixed it weeks ago and Search Console hasn't noticed.