HTMLintroevergreen
Lazy loading and decoding
Load less, sooner.
Defer offscreen images and iframes with loading=lazy, keep the main thread responsive with decoding=async, and tell the browser what matters most with fetchpriority — all native attributes, no observer code.
Deferred image with loading=lazy
HTML+CSS+JSintro Press Run to execute
The eager top image and the loading="lazy" bottom image render identically once visible — the difference is when each is fetched: the lazy one waits until you scroll the 480px .spacer and it nears the viewport, and its width/height reserve the space so nothing shifts when it arrives.