Total image payload on React sites
18.8% of audited sites (1,799) transfer 1 to 3 MB of images and 14.4% exceed 3 MB. Sites staying under 350 KB pass LCP at 92% (1.2s median), compared with 66% (2.0s median) above 3 MB.
38.3% of React sites use under 350 KB of images total image payload, and 92% of those sites have a good LCP, against 85% of all React sites.
LCP pass rate
Sites with under 350 KB of images total image payload have a good LCP most often: 92%, against 85% of all React sites. Sites with over 3 MB of images image payload have it least often, at 66%.
Total image payload usage
Under 350 KB of images is the most used: 38.3% of React sites.
The four LCP phases
Across the four LCP sub-parts in Chrome's field data, the largest gap between under 350 KB of images and over 3 MB of images sits in time to first byte (TTFB): 433 ms median for under 350 KB of images against 931 ms for over 3 MB of images. Overall median field LCP is 1.2s for under 350 KB of images (TTFB 433 ms, load delay 403 ms, load duration 123 ms, render delay 158 ms) versus 2.0s for over 3 MB of images.
Total image payload per platform
On Wix, 50% of sites use under 350 KB of images total image payload, and 94% of Wix sites have a good LCP, against 85% of all sites. On WordPress, 36% of sites use 1 MB to 3 MB of images, and 61% of WordPress sites have a good LCP.
Wix 5,824 sitesUnder 350 KB 50%350 KB to 1 MB 34%1 MB to 3 MB 11%94%
WordPress 2,342 sites1 MB to 3 MB 36%Over 3 MB 35%350 KB to 1 MB 19%61%Total image payload or the platform
Does the platform explain the total image payload difference?
On Wix, 95% of sites with under 350 KB of images total image payload have a good LCP, against 95% of Wix sites with 350 KB to 1 MB of images. Within Wix, sites with under 350 KB of images and 350 KB to 1 MB of images have a good LCP about equally often. On WordPress, 71% of sites with under 350 KB of images total image payload have a good LCP, against 67% of WordPress sites with 350 KB to 1 MB of images. Within WordPress, sites with under 350 KB of images and 350 KB to 1 MB of images have a good LCP about equally often.
How total image weight competes with the hero paint
Even when off-screen images are lazy-loaded, oversized carousels, unresized product grids, and CSS background images compete for cellular bandwidth during initial viewport load. Across 3,661 sites (38.3%) under 350 KB of images, 92% pass field LCP at a 1.2s median, whereas the 14.4% (1,375) exceeding 3 MB drop to 66% good LCP (2.0s median).
Understanding total image payload
Keep total image transfer under 1 MB on initial load by serving AVIF or WebP, matching srcset widths to rendered layout slots, and lazy-loading off-screen media. Across all audited sites, 38.3% stay under 350 KB (92% good LCP, 1.2s median) versus 14.4% above 3 MB (66% good LCP, 2.0s median).
By Arjen Karel · 9,570 crawled React sites (9,110 with all devices Chrome field data, October 2026). How we measured.