In a latest episode of Google’s Search Off the File podcast, Martin Splitt and John Mueller mentioned when lazy loading helps and when it might sluggish pages.
Splitt used a real-world instance on builders.google.com for example a typical sample: making each picture lazy by default can delay Largest Contentful Paint (LCP) if it contains above-the-fold visuals.
Splitt mentioned:
“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 factor, which may push again LCP and trigger structure shifts if dimensions aren’t set.
Splitt mentioned:
“In case you are utilizing lazy loading on a picture that’s instantly seen, that’s almost definitely going to have an effect in your largest contentful paint. It’s like virtually 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 might paint quick.
Once 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 structure and different work progress earlier than it requests the hero picture.
- The hero then competes for bandwidth after scripts, types, and different property have already queued.
That delay shifts the paint time of the biggest factor later, which will increase your LCP.
On sluggish networks or CPU-limited units, the impact is extra noticeable. If width and peak are lacking, the late picture can even nudge structure and really feel “jarring.”
search engine marketing Threat With Some Libraries
Browsers now help a built-in loading attribute for photos and iframes, which removes the necessity for heavy JavaScript in customary eventualities. WordPress adopted native lazy loading by default, serving to it unfold.
Splitt mentioned:
“Browsers obtained a local attribute for photos and iframes, the loading attribute … which makes the browser maintain the lazy loading for you.”
Older or customized lazy-loading libraries can conceal picture URLs in nonstandard attributes. If the actual URL by no means lands in src or srcset within the HTML Google renders, photos could not get picked up for indexing.
Splitt mentioned:
“We’ve seen a number of lazy loading libraries … that use some form of data-source attribute slightly than the supply attribute… If it’s not within the supply attribute, we gained’t decide it up if it’s in some customized attribute.”
How To Verify Your Pages
Use Search Console’s URL Inspection to evaluate the rendered HTML and make sure 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 seems prefer it incorporates all of the picture URLs within the supply attribute of a picture tag … then you’ll be effective.”
Rating Impression
Splitt framed rating results as modest. Core Net Vitals contribute to rating, however he referred to as it “a tiny minute issue normally.”
What You Ought to Do Subsequent
- Hold hero and different above-the-fold photos keen with width and peak set.
- Use native loading=”lazy” for below-the-fold photos and iframes.
- If you happen to depend on a library for previews, movies, or dynamic sections, ensure the ultimate markup exposes actual URLs in customary attributes, and make sure 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 tendencies over time.
Featured Picture: Screenshot from YouTube.com/GoogleSearchCentral, August 2025.
