Total JavaScript payload on React sites
43.8% of audited sites (4,193) transfer over 1 MB of JavaScript. Median field INP climbs from 49ms under 250 KB (100% good INP) to 53ms above 1 MB (99% good INP).
8.3% of React sites use 250 to 550 KB of JavaScript total JavaScript payload, and 100% of those sites have a good INP, against 99% of all React sites.
44.7% of React sites use 550 KB to 1 MB of JavaScript total JavaScript payload, and 90% of those sites have a good LCP, against 79% of all React sites.
Core Web Vitals pass rate
Sites with 250 to 550 KB of JavaScript total JavaScript payload have a good INP most often: 100%, against 99% of all React sites. Sites with over 1 MB of JavaScript JS payload have it least often, at 99%.
Sites with 550 KB to 1 MB of JavaScript total JavaScript payload have a good LCP most often: 90%, against 79% of all React sites. Sites with over 1 MB of JavaScript JS payload have it least often, at 72%.
Total JavaScript payload usage
550 KB to 1 MB of JavaScript is the most used: 44.7% of React sites. 250 to 550 KB of JavaScript is 8.3% of React sites.
Total JavaScript payload per platform
On Wix, 58% of sites use 550 KB to 1 MB of JavaScript total JavaScript payload, and 100% of Wix sites have a good INP, against 99% of all sites. On WordPress, 55% of sites use over 1 MB of JavaScript, and 100% of WordPress sites have a good INP.
On Wix, 58% of sites use 550 KB to 1 MB of JavaScript total JavaScript payload, and 92% of Wix sites have a good LCP, against 79% of all sites. On WordPress, 55% of sites use over 1 MB of JavaScript, and 66% of WordPress sites have a good LCP.
Wix 5,824 sites550 KB to 1 MB 58%Over 1 MB 39%100%92%
WordPress 2,342 sitesOver 1 MB 55%550 KB to 1 MB 25%250 to 550 KB 14%100%66%Total JavaScript payload or the platform
Does the platform explain the total JavaScript payload difference?
On Wix, 100% of sites with 550 KB to 1 MB of JavaScript total JavaScript payload have a good INP, against 100% of Wix sites with over 1 MB of JavaScript. Within Wix, sites with 550 KB to 1 MB of JavaScript and over 1 MB of JavaScript have a good INP about equally often. On WordPress, 100% of sites with 250 to 550 KB of JavaScript total JavaScript payload have a good INP, against 99% of WordPress sites with 550 KB to 1 MB of JavaScript. Within WordPress, sites with 250 to 550 KB of JavaScript and 550 KB to 1 MB of JavaScript have a good INP about equally often.
On Wix, 98% of sites with 550 KB to 1 MB of JavaScript total JavaScript payload have a good LCP, against 86% of Wix sites with over 1 MB of JavaScript. Within Wix, sites with 550 KB to 1 MB of JavaScript have a good LCP more often. On WordPress, 76% of sites with 550 KB to 1 MB of JavaScript total JavaScript payload have a good LCP, against 59% of WordPress sites with over 1 MB of JavaScript. Within WordPress, sites with 550 KB to 1 MB of JavaScript have a good LCP more 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 795 sites (8.3%) shipping 250 to 550 KB of scripts, 100% pass field INP at an 45ms median, whereas the 43.8% (4,193) shipping over 1 MB drop to 99% good INP (53ms median).
Understanding total JavaScript payload
Keep total JavaScript transfer below 550 KB by route-splitting framework bundles, auditing tag-manager containers, and loading interactive widgets on demand. Across all audited sites, 8.3% transfer 250 to 550 KB (100% good INP, 45ms median) versus 43.8% above 1 MB (99% good INP, 53ms median).
By Arjen Karel · 9,570 crawled React sites (1,979 with desktop Chrome field data, October 2026). How we measured.