What does the 2.5-second mark measure?
Google calls it Largest Contentful Paint. It times how long the biggest thing a visitor sees at the top of the page takes to show. On most small business sites, that is the main photo or the headline.
Google's guide says to aim for 2.5 seconds or less on at least 3 out of 4 visits, and to check phones and computers apart. Phones are usually slower, so start there.
Step 1: Test one page for free
Open PageSpeed Insights, Google's free speed test. You don't need an account.
Paste the full address of one page, such as your home page or your busiest service page, and click Analyze. Wait for the report to finish loading.
When it's done, make sure you are on the Mobile tab.
Step 2: Read your mobile number
Find "Largest Contentful Paint" and its number in seconds. Google grades it like this: 2.5 seconds or less is good, anything up to 4 seconds needs improvement, and over 4 seconds is poor.
The report can show two kinds of numbers. The top part shows real visits from the last 28 days, if your page or your site had enough visitors for Google to measure. The lower part is a test Google runs on the spot on a simulated phone. Small sites often see only the test, and that's fine to start with.
Step 3: Find what slows your page down
Google splits the wait into four parts, one after the other. Knowing which part is slow tells you what to fix.
- Your server answersThe first reply from your site
- The browser finds the main imageLate if the page hides it
- The image downloadsSlow if the file is big
- The page draws itDelayed by files it waits for
A slow server is the one to check first. Google's guide says a slow first reply can make 2.5 seconds hard or even impossible to reach. Extra redirects, a server far from your customers, and pages that can't be saved for quick reuse all add to it.
Big images are the other usual cause. A photo straight from a camera or phone is often far larger than the page needs. The page also slows down when the main image is set to load late, or when other files have to load before anything appears.
Step 4: Ask your AI to fix it
If your site's code is on your computer, paste this into Claude Code or Codex from your site's folder:
My home page's Largest Contentful Paint on mobile is over 2.5 seconds in PageSpeed Insights. Find the main image or headline at the top of the page and make it show sooner: make sure it is not lazy-loaded, give it fetchpriority="high", save it at the size the page shows it in a modern format like WebP, and remove anything that blocks the page from drawing it. Show me each change before you make it.If your site is on a website builder, ask your AI how to make the same changes in your builder's settings, or send the request to whoever built your site.