What Is Lazy Loading in Web Development?

What it applies to

Images and videos below the fold on any page — especially long-form pages, blog posts, case study pages, and image galleries where loading all assets at once would significantly delay initial render.

How to implement lazy loading

• Native HTML (simplest): Add loading="lazy" to any <img> or <iframe> element. Supported in all modern browsers — no JavaScript required.
• CSS background images: Cannot be natively lazy loaded. Use the Intersection Observer API in JavaScript to add a class to elements as they enter the viewport, which triggers the background image via CSS.
• Never lazy load: The hero image or the LCP element. Lazy loading the above-the-fold image delays its load and worsens the LCP score — the opposite of the intended effect.

In Webflow

Webflow automatically applies native lazy loading (loading="lazy") to all images below the first content section. For the hero/LCP image, disable lazy loading in the Image Settings panel and add a preload tag via custom code to ensure it loads as early as possible.

What to check after implementation

• Run Google PageSpeed Insights to confirm images are lazy loading correctly.
• Use Chrome DevTools → Network tab with throttling enabled to observe which images load on initial page view vs on scroll.
• Verify in Google Search Console that lazy-loaded content is being indexed correctly.