WordPress total image payload and the Core Web Vitals

Sites with under 350 KB of images total image payload have a good LCP most often: 79%, against 70% of all WordPress sites. Sites with over 3 MB of images image payload have it least often, at 63%.

1 MB to 3 MB of images is the most used: 35.1% of WordPress sites. Under 350 KB of images is 11.5% of WordPress sites.

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): 993 ms median for under 350 KB of images against 1167 ms for over 3 MB of images. Overall median field LCP is 1.7s for under 350 KB of images (TTFB 993 ms, load delay 258 ms, load duration 128 ms, render delay 225 ms) versus 2.1s for over 3 MB of images.

On jQuery, 35% of sites use 1 MB to 3 MB of images total image payload, and 69% of jQuery sites have a good LCP, against 70% of all sites. On Vue, 38% of sites use 1 MB to 3 MB of images, and 67% of Vue sites have a good LCP.

FrameworkTotal image payload on its sitesGood LCP

All WordPress sites 63,295 sites1 MB to 3 MB 35%Over 3 MB 31%350 KB to 1 MB 22%Under 350 KB 12%70%

Alpine 380 sites1 MB to 3 MB 41%Over 3 MB 31%350 KB to 1 MB 21%78%

jQuery 60,314 sites1 MB to 3 MB 35%Over 3 MB 32%350 KB to 1 MB 22%Under 350 KB 11%69%

Vue 4,844 sites1 MB to 3 MB 38%Over 3 MB 34%350 KB to 1 MB 20%67%

React 2,233 sites1 MB to 3 MB 36%Over 3 MB 36%350 KB to 1 MB 20%63%

1 MB to 3 MB Over 3 MB 350 KB to 1 MB Under 350 KB

Does the framework explain the total image payload difference?

On jQuery, 78% of sites with under 350 KB of images total image payload have a good LCP, against 68% of jQuery sites with 1 MB to 3 MB of images. Within jQuery, sites with under 350 KB of images have a good LCP more often. On Vue, 74% of sites with under 350 KB of images total image payload have a good LCP, against 68% of Vue sites with 1 MB to 3 MB of images. Within Vue, sites with under 350 KB of images and 1 MB to 3 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 7,306 sites (11.5%) under 350 KB of images, 79% pass field LCP at a 1.7s median, whereas the 31.2% (19,729) exceeding 3 MB drop to 63% good LCP (2.1s median).