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How can I use lazy-loading to improve lcp and cls metrics?

Asked on Sep 16, 2025

Answer

Lazy-loading can significantly improve your Largest Contentful Paint (LCP) and Cumulative Layout Shift (CLS) metrics by deferring the loading of off-screen images and iframes until they are needed, reducing initial load time and preventing layout shifts.

Example Concept: Lazy-loading is a technique where images and iframes are only loaded when they are about to enter the viewport. This reduces the initial load time and network resource usage, improving LCP by allowing critical content to load faster. Additionally, it helps stabilize layout by preventing images from loading and shifting content unexpectedly, thus improving CLS.

Additional Comment:
  • Use the "loading='lazy'" attribute on images and iframes to enable native lazy-loading in modern browsers.
  • Ensure that critical images, such as hero images, are not lazy-loaded to avoid delaying LCP.
  • Monitor the impact of lazy-loading on user experience to ensure it doesn't delay content visibility unnecessarily.
  • Test your site with tools like Lighthouse to measure improvements in LCP and CLS after implementing lazy-loading.
✅ Answered with Core Web Vitals best practices.

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