In a recent episode of Google’s Search Off the Report podcast, Martin Splitt and John Mueller mentioned when lazy loading helps and when it may gradual pages.

Splitt used a real-world instance on builders.google.com as an instance a typical sample: making each picture lazy by default can delay Largest Contentful Paint (LCP) if it consists of above-the-fold visuals.

Splitt stated:

“The content material administration system that we’re utilizing for builders.google.com … defaults all photos to lazy loading, which isn’t nice.”

Splitt used the instance to elucidate why lazy-loading hero photos is dangerous: you inform the browser to attend on essentially the most seen ingredient, which may push again LCP and trigger format shifts if dimensions aren’t set.

Splitt stated:

“If you’re utilizing lazy loading on a picture that’s instantly seen, that’s almost certainly going to have an effect in your largest contentful paint. It’s like nearly assured.”

How Lazy Loading Delays LCP

LCP measures the second the biggest textual content or picture within the preliminary viewport is painted.

Usually, the browser’s preload scanner finds that hero picture early and fetches it with excessive precedence so it may paint quick.

While you add loading="lazy" to that very same hero, you alter the browser’s scheduling:

  • The picture is handled as decrease precedence, so different sources begin first.
  • The browser waits till format and different work progress earlier than it requests the hero picture.
  • The hero then competes for bandwidth after scripts, kinds, and different property have already queued.

That delay shifts the paint time of the biggest ingredient later, which will increase your LCP.

On gradual networks or CPU-limited units, the impact is extra noticeable. If width and top are lacking, the late picture may also nudge format and really feel “jarring.”

search engine marketing Danger With Some Libraries

Browsers now help a built-in loading attribute for photos and iframes, which removes the necessity for heavy JavaScript in normal eventualities. WordPress adopted native lazy loading by default, serving to it unfold.

Splitt stated:

“Browsers obtained a local attribute for photos and iframes, the loading attribute … which makes the browser deal with the lazy loading for you.”

Older or customized lazy-loading libraries can cover picture URLs in nonstandard attributes. If the true URL by no means lands in src or srcset within the HTML Google renders, photos could not get picked up for indexing.

Splitt stated:

“We’ve seen a number of lazy loading libraries … that use some kind of data-source attribute slightly than the supply attribute… If it’s not within the supply attribute, we received’t decide it up if it’s in some customized attribute.”

How To Examine Your Pages

Use Search Console’s URL Inspection to evaluate the rendered HTML and ensure that above-the-fold photos and lazy-loaded modules resolve to plain attributes. Keep away from counting on the screenshot.

Splitt suggested:

“If the rendered HTML appears to be like prefer it comprises all of the picture URLs within the supply attribute of a picture tag … then you’ll be advantageous.”

Rating Affect

Splitt framed rating results as modest. Core Web Vitals contribute to rating, however he known as it “a tiny minute issue usually.”

What You Ought to Do Subsequent

  • Preserve hero and different above-the-fold photos keen with width and top set.
  • Use native loading="lazy" for below-the-fold photos and iframes.
  • Should you depend on a library for previews, movies, or dynamic sections, make certain the ultimate markup exposes actual URLs in normal attributes, and ensure in rendered HTML.

Trying Forward

Lazy loading is helpful when utilized selectively. Deal with it as an opt-in for noncritical content material.

Confirm your implementation with rendered HTML, and watch how your LCP developments over time.

Featured Picture: Screenshot from YouTube.com/GoogleSearchCentral, August 2025. 


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