The State of Web Vitals

Main-thread CPU breakdown and the Core Web Vitals

26.8% of audited sites (55,256) spend over 1,200ms in main-thread scripting during load, pushing median field INP to 56ms (99% good INP) versus 46ms (99% good INP) at 150 to 450ms.

Field data PhoneDesktopAll Scope All sites October 2026 edition · Desktop field outcomes

25.8% of sites use 450 to 1,200ms of scripting CPU main-thread CPU breakdown, and 99% of those sites have a good INP, against 99% of all sites.

The State of Web Vitals · October 2026 · 210,902 crawled sites · 69,745 with desktop field data · 206,258 sites with main-thread CPU breakdownBy Arjen Karel · corewebvitals.io/state-of-cwv
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INP pass rate

Sites with 450 to 1,200ms of scripting CPU main-thread CPU breakdown have a good INP most often: 99%, against 99% of all sites. Sites with over 1,200ms of scripting CPU scripting CPU have it least often, at 99%.

SitesGood, needs improvement, poor INPMedian
All sites69,74599%49ms
450 to 1,200ms scripting CPU 25.8%18,37299%50ms
150 to 450ms scripting CPU 23.6%15,16699%46ms
Under 150ms scripting CPU 23.8%14,51399%44ms
Over 1,200ms scripting CPU 26.8%21,69499%56ms
GoodNeeds improvementPoorSites: with Chrome field data
The State of Web Vitals · October 2026 · 210,902 crawled sites · 69,745 with desktop field data · 206,258 sites with main-thread CPU breakdownBy Arjen Karel · corewebvitals.io/state-of-cwv
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Main-thread CPU breakdown usage

Over 1,200ms of scripting CPU is the most used: 26.8% of sites. 450 to 1,200ms of scripting CPU is 25.8% of sites.

Over 1,200ms scripting CPU 26.8% 450 to 1,200ms scripting CPU 25.8% Under 150ms scripting CPU 23.8% 150 to 450ms scripting CPU 23.6%
Over 1,200ms scripting CPU 26.8% 450 to 1,200ms scripting CPU 25.8% Under 150ms scripting CPU 23.8% 150 to 450ms scripting CPU 23.6%
The State of Web Vitals · October 2026 · 210,902 crawled sites · 69,745 with desktop field data · 206,258 sites with main-thread CPU breakdownBy Arjen Karel · corewebvitals.io/state-of-cwv
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Main-thread CPU breakdown per platform

On WordPress, 36% of sites use over 1,200ms of scripting CPU main-thread CPU breakdown, and 100% of WordPress sites have a good INP, against 99% of all sites. On Shopify, 47% of sites use over 1,200ms of scripting CPU, and 99% of Shopify sites have a good INP.

PlatformMain-thread CPU breakdown on its sitesGood INP
Sites with main-thread CPU breakdown 206,258 sitesOver 1,200ms scripting CPU 27%450 to 1,200ms scripting CPU 26%Under 150ms scripting CPU 24%150 to 450ms scripting CPU 24%99%
Adobe Commerce 1,095 sitesOver 1,200ms scripting CPU 51%450 to 1,200ms scripting CPU 32%150 to 450ms scripting CPU 10%100%
Wix 5,825 sites450 to 1,200ms scripting CPU 44%150 to 450ms scripting CPU 32%Over 1,200ms scripting CPU 23%100%
Squarespace 2,258 sitesOver 1,200ms scripting CPU 48%450 to 1,200ms scripting CPU 33%150 to 450ms scripting CPU 17%100%
Joomla 2,551 sitesUnder 150ms scripting CPU 28%150 to 450ms scripting CPU 26%Over 1,200ms scripting CPU 25%450 to 1,200ms scripting CPU 21%100%
Drupal 3,296 sites150 to 450ms scripting CPU 28%Under 150ms scripting CPU 27%450 to 1,200ms scripting CPU 24%Over 1,200ms scripting CPU 21%100%
WordPress 65,509 sitesOver 1,200ms scripting CPU 36%450 to 1,200ms scripting CPU 29%150 to 450ms scripting CPU 21%Under 150ms scripting CPU 14%100%
Shopify 8,573 sitesOver 1,200ms scripting CPU 47%450 to 1,200ms scripting CPU 32%150 to 450ms scripting CPU 17%99%
Over 1,200ms scripting CPU 450 to 1,200ms scripting CPU Under 150ms scripting CPU 150 to 450ms scripting CPU
The State of Web Vitals · October 2026 · 210,902 crawled sites · 69,745 with desktop field data · 206,258 sites with main-thread CPU breakdownBy Arjen Karel · corewebvitals.io/state-of-cwv
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Main-thread CPU breakdown or the platform

Does the platform explain the main-thread CPU breakdown difference?

On WordPress, 100% of sites with 450 to 1,200ms of scripting CPU main-thread CPU breakdown have a good INP, against 99% of WordPress sites with over 1,200ms of scripting CPU. Within WordPress, sites with 450 to 1,200ms of scripting CPU have a good INP more often. On Shopify, 100% of sites with 450 to 1,200ms of scripting CPU main-thread CPU breakdown have a good INP, against 99% of Shopify sites with over 1,200ms of scripting CPU. Within Shopify, sites with 450 to 1,200ms of scripting CPU and over 1,200ms of scripting CPU have a good INP about equally often.

Why scripting dominates main-thread CPU budgets

Across the web, JavaScript evaluation accounts for the largest share of total main-thread CPU time, dwarfing HTML parsing, style calculation, and painting. Across 48,644 sites (23.6%) spending 150 to 450ms in scripting CPU, 99% pass field INP (46ms median), while the 26.8% (55,256) exceeding 1,200ms drop to 99% good INP (56ms median).

The State of Web Vitals · October 2026 · 210,902 crawled sites · 69,745 with desktop field data · 206,258 sites with main-thread CPU breakdownBy Arjen Karel · corewebvitals.io/state-of-cwv
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Understanding main-thread CPU breakdown

Audit scripts consuming over 450ms of CPU during boot and yield between hydration, analytics initialization, and DOM manipulation. Across all audited sites, 23.6% spend 150 to 450ms in scripting CPU (99% good INP, 46ms median) versus 26.8% above 1,200ms (99% good INP, 56ms median).

Go fix it Yield to the main thread → Fix excessive DOM size → JavaScript priority levels →
The State of Web Vitals · October 2026 · 210,902 crawled sites · 69,745 with desktop field data · 206,258 sites with main-thread CPU breakdownBy Arjen Karel · corewebvitals.io/state-of-cwv
Related signals Document lifecycle (lab) → Lab paint timeline → Total Blocking Time (lab) → By Arjen Karel · 210,902 crawled sites (69,745 with desktop Chrome field data, 206,258 sites with main-thread CPU breakdown, October 2026) · How we measured