Effects of Too Much Lazy Loading on Web Performance

Lazy loading is a widely‑adopted web standard that defers the loading of resources until they are needed, typically using the loading="lazy" attribute on img or iframe elements. This technique can reduce page‑load time (PLT) and lower resource consumption, especially on low‑end mobile devices.

However, excessive lazy loading introduces several performance problems. It can slow down rapid scrolling because the browser must wait for resources to load before rendering, cause noticeable delays when images lack explicit width and height attributes, and lead to content buffering where resources are still downloading while the user scrolls quickly, especially on slow connections.

These issues also affect SEO: search engine crawlers may miss lazily‑loaded content that is not visible without user interaction, causing important information to be omitted from indexes.

To use lazy loading wisely, follow these recommendations:

Apply lazy loading only to resources that are outside the initial viewport or in collapsed sections, avoiding critical assets such as JavaScript components, background images, or media needed for immediate interaction.

Target non‑essential, non‑visible content, and ensure proper error handling and fallback for browsers that do not support native lazy loading.

Do not lazy‑load content that is important for SEO, such as keywords or core business information.

By carefully selecting what to lazy‑load and monitoring with tools like Chrome Lighthouse, developers can reap the benefits of reduced load time without sacrificing user experience or search visibility.

In summary, lazy loading is a powerful optimization tool, but over‑application can degrade performance; balanced use leads to noticeable improvements.

<img
  src="bits.jpeg"
  loading="lazy"
  alt="an image of a laptop" />

<iframe
  src="about-page.html"
  loading="lazy"></iframe>