Lazy loading delays downloading images and iframes until they are about to scroll into view. Adding the native loading="lazy" attribute to offscreen media means the browser skips loading it during the initial page load, which cuts initial page weight and speeds up the first render.

No. Images visible in the first viewport, especially your Largest Contentful Paint image (like a hero banner), should load eagerly. Lazy-loading above-the-fold images delays them and can hurt your LCP score. This tool counts what's not lazy so you can decide which offscreen assets to defer.

Yes, when applied correctly. Deferring offscreen images reduces the bytes and network contention during initial load, improving Largest Contentful Paint and reducing the total work the browser does up front. The key is to lazy-load only what is below the fold and keep the LCP element eager.

Native loading="lazy" is supported in all modern browsers including Chrome, Edge, Firefox, and Safari. Older browsers simply ignore the attribute and load the image normally, so there is no downside to adding it. It is the simplest, dependency-free way to lazy-load.

Yes. Iframes such as embedded YouTube videos, maps, and social widgets are often heavy and benefit greatly from loading="lazy". This tool counts iframes missing the attribute separately from images, since iframe embeds are frequently the single largest deferrable resource on a page.

Many sites use JavaScript lazy-loading libraries that store the real URL in data-src and load it on scroll. Those images may not have loading="lazy" but are still deferred. This tool focuses on the native attribute; if you use a JS library, a flagged image may already be lazy through that mechanism.

Add the loading="lazy" attribute to the img or iframe tag for any element below the fold: <img src="photo.jpg" loading="lazy" alt="...">. Leave the first hero or LCP image without it. Re-run the checker afterward to confirm the eager count has dropped.