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Barry shows here a few ways to prevent layout shifts and make your visitors happier.
All of these techniques basically involve setting aside the correct amount of space before additional content is loaded — whether that is media or JavaScript-injected content, but there’s a few different options available to web developers to do this.
Apparently, an image whose part above the fold is indeed the largest, but of which only a small part can be seen, can be considered an LCP element, even if another image has a larger part visible... 😭
You can see this for my photography site in this WebPageTest result:
https://www.webpagetest.org/vitals.php?test=230606_BiDcN4_4NJ&run=3&cached=0#lcp
Watch Out for Layout Shifts with ‘ch’ Units
In our case, we were using ch units to define our page layout. This meant that our post content was equal to 50ch units (or the width of fifty…
Limiting the image density on mobile devices drasticaly improves performance, with no visual loss, so we did it!
I still wish it was much easier than dealing with <picture> and x descriptors for fluid images… 😞
With a <img maxdensity="2.5" …> attribute for example!
If you agree, comment:
https://github.com/whatwg/html/issues/4421
I love #SpeedCurve's simple and efficient Core Web Vitals Real User Monitoring, especially when everything is green! 🥳
This is a real e-commerce site, with many real users everyday. After a few months of performance optimisation.
Largest Contentul Paint change in Chrome 112 to ignore low-entropy images
This may result in LCP times increasing, if a low-content background was being painted very early, or if a low-content placeholder was being used…
Barry Pollard 
Paul Hebert