**Images are usually the heaviest thing on a page — and the easiest big speed win.** This check looks at whether your images are optimised: served in modern formats, sized to how they're displayed, compressed, and given explicit dimensions. Oversized, uncompressed images bloat page weight, slow down loading, and cause layout shifts — all of which hurt your speed metrics and the experience.
It looks at how your images are delivered and whether they're slowing the page down. Specifically:
- Modern formats — whether images use efficient formats like WebP or AVIF rather than large legacy JPEG/PNG.
- Right-sizing — whether images are sized to their display dimensions, not served far larger and scaled down by the browser.
- Compression — whether images are compressed to a sensible quality rather than shipped at full weight.
- Dimensions set — whether width and height are declared so images don't cause layout shift.
Well-optimised images pass; some oversized or unoptimised images is a warning; heavy, unoptimised images significantly slowing the page is a fail.
GEObubbly inspects the page's images for format, size, compression and declared dimensions. It's an extended Performance & Mobile UX check that runs against the page's image assets.
On most pages, images account for the largest share of page weight, so optimising them is often the single biggest performance win available. Four things matter. Format: modern formats like WebP and AVIF deliver the same visual quality at a fraction of the size of legacy JPEG and PNG. Sizing: serving a 3000px image into a 600px slot forces the user to download many times the data they need, so images should be sized — or served responsively with srcset — to their actual display size. Compression: most images can be compressed substantially with no visible loss. Dimensions: declaring width and height lets the browser reserve space, preventing the layout shift that hurts CLS. The hero image is frequently the LCP element, so optimising it directly improves loading metrics. Lighter images mean faster pages for users, better Core Web Vitals, and a site that's cheaper for crawlers to fetch. Descriptive alt text adds accessibility and image-search value on top.
Optimising images comes down to four steps. First, use a modern format like WebP or AVIF, which are far smaller than JPEG or PNG at the same quality. Second, size images to how they're actually displayed — don't serve a huge file into a small slot — and use responsive srcset to give different sizes to different screens. Third, compress them to a sensible quality, since most images shrink dramatically with no visible loss. Fourth, set explicit width and height so the browser reserves space and the layout doesn't shift as they load.
Generally yes. WebP and AVIF are modern image formats that deliver the same visual quality as JPEG and PNG at significantly smaller file sizes, which directly reduces page weight and speeds up loading. Both are widely supported in current browsers, and you can provide a JPEG/PNG fallback with the <picture> element for any older client. AVIF typically compresses even better than WebP but takes longer to encode. For most sites, switching photographic images to WebP or AVIF is one of the easiest, highest-impact performance improvements available.
Declaring width and height (or a CSS aspect-ratio) lets the browser reserve the right amount of space for an image before it loads, so surrounding content doesn't jump when the image appears. That prevents layout shift, which is exactly what the Cumulative Layout Shift (CLS) Core Web Vital measures. Without declared dimensions, images load into zero-height space and then push everything down, producing the janky reflow that frustrates users and damages your CLS score. It's a small, mechanical fix with a real impact on perceived quality.
Often dramatically, because images are usually the largest component of page weight. An oversized, uncompressed hero image can be several megabytes on its own — frequently the single biggest cause of a slow Largest Contentful Paint, since the hero is often the LCP element. Multiply that across a gallery of unoptimised images and the page can take many seconds to load on a mobile connection. Conversely, converting to modern formats, right-sizing and compressing can cut image weight by 70% or more, which is why image optimisation is such a high-leverage fix.
Yes. Faster-loading pages from lighter images improve Core Web Vitals and page experience, which feed Google's ranking signals, and well-optimised images with descriptive alt text also help image search and accessibility. For crawling, lighter pages are cheaper to fetch, so engines — including AI crawlers — can cover more of your site per visit. Image optimisation isn't a direct GEO ranking factor, but it supports the speed, accessibility and crawl efficiency that underpin a healthy site for both search and AI engines.