Mozilla adds support for image lazy loading to Firefox 75. Currently, the feature is not enabled by default, but users can enable it in the latest Nightly version and test it on their own on the late-loaded demo site. Previously, Google had enabled lazy loading for iframes and images in Chrome.
Firefox’s latest version of Nightly supports the lazyloading syntax.
Enable lazy loading of images in Firefox
1. Launch Firefox Nightly Browser
2. Visit: config
3. Search for “lazy” and, in the highlighted results, change the dom.image-lazy-lazy-enabled pref value to true
4. Now, restart your browser, access IMG loading lazy demo site, and try scrolling down to see that pictures of the cat will load again and again. You can also see at the top that the “loading” value for HTMLImageElement.prototype is true, which appears as false in non-Nightly versions.
And as you scroll down to the bottom of the page, you can also observe the order in which cat pictures are loaded in Firefox’s developer tool, Network Panel.
The good news is that image late loading will also become part of WordPress Core, and wordPress plug-ins such as W3 Total Cache and Auto Optimize are already available that provide site owners with the option to delay loading off-screen images to take advantage of A good user experience.