Lazy Loading
Lazy loading is a technique in which images, videos or other resources are loaded only shortly before they enter the visible area of the screen, instead of loading all of a page's content immediately, which reduces the initial page size and load time.
In practice
Modern browsers support the native HTML attribute `loading="lazy"` for images, with no additional JavaScript library. One caveat: images that are visible without scrolling – above all the LCP image – must never be lazy loaded. Google puts it categorically: "Never lazy-load your LCP image." According to the HTTP Archive's Web Almanac 2025, that still happens on 16 to 17 per cent of all pages, needlessly delaying the image request. Lazy loading belongs only on images that come into view once the visitor scrolls.