Lazy loading is deferring the loading of resources — images, iframes, videos, sometimes components — until they are about to enter the viewport, rather than loading everything when the page first loads.
Definition
Lazy loading is deferring the loading of resources — images, iframes, videos, sometimes components — until they are about to enter the viewport, rather than loading everything when the page first loads. It reduces the initial payload and speeds up first render, which helps page speed and Core Web Vitals, and it saves bandwidth for content the user never scrolls to.
Modern browsers support it natively for images and iframes with a simple attribute; more advanced setups use intersection observers.
The important caveat is that the Largest Contentful Paint element and anything above the fold must not be lazy loaded — deferring the hero image delays LCP and makes the page slower on the metric that matters. Lazy loading is for below-the-fold content.
In context
For an iGaming affiliate, lazy loading is a straightforward performance win on the content-heavy pages this niche produces — review pages with many screenshots, comparison pages with rows of operator logos, guides with multiple images, and any page embedding demo games, videos or third-party widgets. Deferring all of that below-the-fold content until the user scrolls near it cuts the initial load substantially.
The implementation points: use native lazy loading (loading="lazy") on below-the-fold images and iframes; explicitly do not lazy load the LCP element or above-the-fold images (mark them eager or leave them default and preload the LCP one); always set width and height on lazy-loaded images so their space is reserved and they do not cause layout shift (CLS) when they load; and lazy load heavy embeds like demo games, video players and chat widgets so they do not block initial render. Done correctly this improves LCP, INP and CLS together; done carelessly (lazy loading the hero, or omitting dimensions) it hurts them.
For affiliate-facing content, the framing is that lazy loading defers below-the-fold images, iframes and heavy embeds until they are near the viewport to speed initial load, that the LCP element and above-the-fold content must never be lazy loaded, that lazy-loaded images still need explicit dimensions to avoid layout shift, and that on an image- and embed-heavy affiliate site it is a reliable Core Web Vitals improvement.
Worked example
An affiliate adds native lazy loading to all below-the-fold images, screenshots and embedded demo games on its review pages, keeps the hero image eager and preloaded, and sets explicit dimensions on every image. Initial page weight drops sharply, LCP and INP improve, and CLS stays low because the lazy images have reserved space.
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