Checks
Oversized images
Flags images heavier than 300 kB as a warning and over 1000 kB as a failure, since unnecessarily large image files are one of the most common causes of slow pages.
What this check looks for
For images the crawler could measure in bytes, this check flags any over 300 kB. If the largest offender exceeds 1000 kB, the whole result fails; otherwise it warns. Images the crawler couldn't measure, or a page with no images, report "na". A page where every measured image stays at or under 300 kB passes.
Why it matters
Image weight is usually the single biggest contributor to page load time, and a slow-loading page directly hurts Core Web Vitals like Largest Contentful Paint — which is itself a ranking factor and a checked metric elsewhere in this report. Heavy images also cost more on mobile data connections, where users are more likely to abandon a slow page before it even finishes rendering. While AI crawlers don't render pages visually the way a browser does, a site that ships bloated, unoptimized images signals a general lack of technical care that tends to correlate with other quality problems a model or a person would notice.
How to fix it
Compress and resize images to match their actual display dimensions:
<!-- 1.4 MB original JPEG served at full camera resolution -->
<img src="/hero-original.jpg" alt="Acme wireless headphones"><!-- Compressed, resized, and served responsively -->
<img
src="/hero-800.webp"
srcset="/hero-800.webp 800w, /hero-1600.webp 1600w"
sizes="(max-width: 800px) 100vw, 800px"
alt="Acme wireless headphones"
>Run images through a compressor (WebP or AVIF at 75-85% quality is usually visually lossless) and never ship a camera-resolution original directly to the browser.
See how your site scores on this check