Total JavaScript payload and the Core Web Vitals
25.4% of audited sites (49,904) transfer over 1 MB of JavaScript. Median field INP climbs from 79ms under 250 KB (95% good INP) to 99ms above 1 MB (92% good INP).
24.8% of sites use 250 to 550 KB of JavaScript total JavaScript payload, and 97% of those sites have a good INP, against 95% of all sites.
25.0% of sites use under 250 KB of JavaScript total JavaScript payload, and 91% of those sites have a good LCP, against 82% of all sites.
Core Web Vitals pass rate
Sites with 250 to 550 KB of JavaScript total JavaScript payload have a good INP most often: 97%, against 95% of all sites. Sites with over 1 MB of JavaScript JS payload have it least often, at 92%.
Sites with under 250 KB of JavaScript total JavaScript payload have a good LCP most often: 91%, against 82% of all sites. Sites with over 1 MB of JavaScript JS payload have it least often, at 74%.
Total JavaScript payload usage
Over 1 MB of JavaScript is the most used: 25.4% of sites. 250 to 550 KB of JavaScript is 24.8% of sites.
Understanding total JavaScript payload
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 48,765 sites (24.8%) shipping 250 to 550 KB of scripts, 97% pass field INP at an 83ms median, whereas the 25.4% (49,904) shipping over 1 MB drop to 92% good INP (99ms median).
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, 24.8% transfer 250 to 550 KB (97% good INP, 83ms median) versus 25.4% above 1 MB (92% good INP, 99ms median).
How total JavaScript payload plays out per platform
What the field data shows when you isolate a single CMS or framework.
WordPress 65,484 sites 24% of WordPress sites ship over 1 MB of JavaScript (93ms median INP vs 79ms under 250 KB).
Across WordPress sites, 24% transfer over 1 MB of scripts (93ms median INP, 97% pass rate) and 21% transfer under 250 KB (79ms median INP, 98% pass rate).
Shopify 8,573 sites 58% of Shopify stores transfer over 1 MB of JavaScript (94% good INP vs 99% at 250 to 550 KB).
Across Shopify storefronts, 58% load more than 1 MB of scripts (94% good INP, 110ms median) compared with 99% (80ms median) on stores transferring 250 to 550 KB.
React 9,570 sites 89% of React sites ship over 550 KB of JavaScript bundles.
Across React sites, 45% transfer 550 KB to 1 MB of JavaScript (97% INP pass rate, 73ms median) and 44% exceed 1 MB (94% pass rate, 87ms median).
By Arjen Karel · 210,902 crawled sites (196,263 with all devices Chrome field data, 196,339 sites with total JavaScript payload, October 2026). How we measured.