LCP is a measurement of how long it takes your page’s important content to load and FID is determined by how long a user has to wait before interacting with your page. These are things you probably should have been optimizing for in the past, as pages with poor scores generally have bad user retention. Changing what’s hosted where, making sure your backend doesn’t have any bottlenecks, and getting rid of unnecessary page elements can help with both of these metrics. For getting an idea of how your page scores, look no further than the official Chrome DevTools package, a set of helpful resources that you can integrate into your local Chrome browser to help develop and optimize websites. The particular tool you’ll want to nab is called “Chrome User Experience Report,” although you should look through the rest of the package for things you might be able to leverage.
The third score, CLS, is somewhat more complicated. It’s a metric of how much the elements on your page move around in ‘unexpected’ ways. A common user frustration when loading up a website is seeing the element they’re trying to interact with go flying down the screen when a graphic load on top of it, or when a giant pop-up appears as a user scrolls down through an article they’re trying to read. News sites tend to be particularly poor at this, so expect a lot of restructuring of your favorite networks and newspapers’ websites in 2021.
Like FID and LCP, you can look at your site’s CLS score with the Chrome User Experience Report. Unlike the other two metrics, however, fixing a poor CLS score might involve a lot of changes to the code of your site. It’s going to be increasingly important to make sure that elements on your page load in the right spot regardless of whether or not other elements on your page have loaded. If you use a CMS, you may need to switch to a different theme or even edit your site’s CSS manually. The results should be worth it, however, as you’ll outpace any competing websites that don’t put in the same amount of work.