Total JavaScript payload and the Core Web Vitals

Sites with under 250 KB of JavaScript total JavaScript payload have a good INP most often: 99%, against 99% of all sites. Sites with over 1 MB of JavaScript JS payload have it least often, at 98%.

Sites with under 250 KB of JavaScript total JavaScript payload have a good LCP most often: 92%, against 86% of all sites. Sites with over 1 MB of JavaScript JS payload have it least often, at 81%.

Over 1 MB of JavaScript is the most used: 25.4% of sites. Under 250 KB of JavaScript is 25.0% of sites.

On WordPress, 27% of sites use 550 KB to 1 MB of JavaScript total JavaScript payload, and 100% of WordPress sites have a good INP, against 99% of all sites. On Shopify, 58% of sites use over 1 MB of JavaScript, and 99% of Shopify sites have a good INP.

On WordPress, 27% of sites use 550 KB to 1 MB of JavaScript total JavaScript payload, and 76% of WordPress sites have a good LCP, against 86% of all sites. On Shopify, 58% of sites use over 1 MB of JavaScript, and 97% of Shopify sites have a good LCP.

PlatformTotal JavaScript payload on its sitesGood INP

Sites with total JavaScript payload 197,692 sitesOver 1 MB 25%Under 250 KB 25%250 to 550 KB 25%550 KB to 1 MB 25%99%

Adobe Commerce 1,102 sitesOver 1 MB 69%550 KB to 1 MB 22%100%

Wix 5,873 sites550 KB to 1 MB 58%Over 1 MB 39%100%

Squarespace 2,275 sitesOver 1 MB 86%550 KB to 1 MB 14%100%

Joomla 2,569 sitesUnder 250 KB 49%250 to 550 KB 30%550 KB to 1 MB 16%100%

Drupal 3,322 sites250 to 550 KB 32%Under 250 KB 27%550 KB to 1 MB 24%Over 1 MB 17%100%

WordPress 65,914 sites550 KB to 1 MB 27%250 to 550 KB 27%Over 1 MB 24%Under 250 KB 21%100%

Shopify 8,634 sitesOver 1 MB 58%550 KB to 1 MB 24%250 to 550 KB 16%99%

Over 1 MB Under 250 KB 250 to 550 KB 550 KB to 1 MB

Does the platform explain the total JavaScript payload difference?

On WordPress, 100% of sites with under 250 KB of JavaScript total JavaScript payload have a good INP, against 99% of WordPress sites with over 1 MB of JavaScript. Within WordPress, sites with under 250 KB of JavaScript and over 1 MB of JavaScript have a good INP about equally often. On Shopify, 99% of sites with over 1 MB of JavaScript total JavaScript payload have a good INP, against 100% of Shopify sites with 250 to 550 KB of JavaScript. Within Shopify, sites with over 1 MB of JavaScript and 250 to 550 KB of JavaScript have a good INP about equally often.

On WordPress, 88% of sites with under 250 KB of JavaScript total JavaScript payload have a good LCP, against 68% of WordPress sites with over 1 MB of JavaScript. Within WordPress, sites with under 250 KB of JavaScript have a good LCP more often. On Shopify, 96% of sites with over 1 MB of JavaScript total JavaScript payload have a good LCP, against 98% of Shopify sites with 250 to 550 KB of JavaScript. Within Shopify, sites with over 1 MB of JavaScript and 250 to 550 KB of JavaScript have a good LCP about equally often.

Why total script weight taxes main-thread responsiveness

Every kilobyte of JavaScript downloaded over the network must be decompressed, parsed, compiled, and evaluated on the CPU. Across 49,094 sites (24.8%) shipping 250 to 550 KB of scripts, 99% pass field INP at an 45ms median, whereas the 25.4% (50,277) shipping over 1 MB drop to 98% good INP (60ms median).