Total JavaScript payload on React sites
43.8% of audited sites (4,193) transfer over 1 MB of JavaScript. Median field INP climbs from 82ms under 250 KB (96% good INP) to 87ms above 1 MB (94% good INP).
44.7% of React sites use 550 KB to 1 MB of JavaScript total JavaScript payload, and 97% of those sites have a good INP, against 95% of all React sites.
44.7% of React sites use 550 KB to 1 MB of JavaScript total JavaScript payload, and 92% of those sites have a good LCP, against 85% of all React sites.
Core Web Vitals pass rate
Sites with 550 KB to 1 MB of JavaScript total JavaScript payload have a good INP most often: 97%, against 95% of all React sites. Sites with 250 to 550 KB of JavaScript JS payload have it least often, at 91%.
Sites with 550 KB to 1 MB of JavaScript total JavaScript payload have a good LCP most often: 92%, against 85% of all React sites. Sites with over 1 MB of JavaScript JS payload have it least often, at 76%.
Total JavaScript payload usage
550 KB to 1 MB of JavaScript is the most used: 44.7% of React sites.
Total JavaScript payload per platform
Wix sets the total JavaScript payload to 550 KB to 1 MB of JavaScript on 58% of its sites, and 97% of Wix sites have a good INP, against 95% of all sites. WordPress sets the total JavaScript payload to over 1 MB of JavaScript on 55% of its sites, and 98% of WordPress sites have a good INP.
Wix sets the total JavaScript payload to 550 KB to 1 MB of JavaScript on 58% of its sites, and 94% of Wix sites have a good LCP, against 85% of all sites. WordPress sets the total JavaScript payload to over 1 MB of JavaScript on 55% of its sites, and 61% of WordPress sites have a good LCP.
WordPress 2,342 sitesOver 1 MB 55%550 KB to 1 MB 25%250 to 550 KB 14%98%61%
Wix 5,824 sites550 KB to 1 MB 58%Over 1 MB 39%97%94%Total JavaScript payload or the platform
Does the platform explain the total JavaScript payload difference?
On Wix, 97% of sites with 550 KB to 1 MB of JavaScript total JavaScript payload have a good INP, against 97% 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, 99% of sites with 550 KB to 1 MB of JavaScript total JavaScript payload have a good INP, against 98% of WordPress sites with over 1 MB of JavaScript. Within WordPress, sites with 550 KB to 1 MB of JavaScript and over 1 MB of JavaScript have a good INP about equally often.
On Wix, 97% of sites with 550 KB to 1 MB of JavaScript total JavaScript payload have a good LCP, against 91% 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, 70% of sites with 550 KB to 1 MB of JavaScript total JavaScript payload have a good LCP, against 52% 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, 91% pass field INP at an 84ms median, whereas the 43.8% (4,193) shipping over 1 MB drop to 94% good INP (87ms 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 (91% good INP, 84ms median) versus 43.8% above 1 MB (94% good INP, 87ms median).
By Arjen Karel · 9,570 crawled React sites (9,110 with all devices Chrome field data, October 2026). How we measured.