The State of Web Vitals

Total Blocking Time (TBT) on React sites

31.2% of audited sites (2,989) record 0ms of lab Total Blocking Time (97% good field INP, 73ms median) and 40.8% stay within 1 to 200ms (95% good INP), while the 13.7% exceeding 600ms TBT drop to 93% good INP (94ms median).

Field data PhoneDesktopAll Scope All sites October 2026 edition · All devices field outcomes · React sites only
React Scoped to 9,570 sites out of 210,902 analyzed (frameworks) Compare with all sites →

One in three React sites, 31.2%, have no lab Total Blocking Time (TBT). Of the 68.8% that do, 59% use 1 to 200ms TBT, and 95% of those sites have a good INP, against 95% of all React sites.

The State of Web Vitals · October 2026 · React: 9,570 crawled sites · 9,110 with all devices field dataBy Arjen Karel · corewebvitals.io/state-of-cwv
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INP pass rate

Sites with 1 to 200ms TBT lab Total Blocking Time (TBT) have a good INP most often: 95%, against 95% of all React sites. Sites with over 600ms TBT Total Blocking Time have it least often, at 93%.

SitesGood, needs improvement, poor INPMedian
All React sites9,11095%80ms
0ms TBT (Zero long tasks) 31.2%2,83097%73ms
1ms to 200ms TBT (Good) 40.8%3,71095%80ms
201ms to 600ms TBT (Needs Improvement) 14.3%1,31593%89ms
Over 600ms TBT (Poor) 13.7%1,25593%94ms
GoodNeeds improvementPoorSites: with Chrome field data
The State of Web Vitals · October 2026 · React: 9,570 crawled sites · 9,110 with all devices field dataBy Arjen Karel · corewebvitals.io/state-of-cwv
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Lab Total Blocking Time (TBT) usage

Two in three React sites uses lab Total Blocking Time (TBT), and three in five of those use 1 to 200ms TBT.

All React sites 9,570 sites
0ms TBT (Zero long tasks) 31.2% Lab Total Blocking Time (TBT) 68.8%
Sites with lab Total Blocking Time (TBT) 6,581 sites
1ms to 200ms TBT (Good) 59.4% 201ms to 600ms TBT (Needs Improvement) 20.8% Over 600ms TBT (Poor) 19.9%
1ms to 200ms TBT (Good) 59.4% 201ms to 600ms TBT (Needs Improvement) 20.8% Over 600ms TBT (Poor) 19.9%
The State of Web Vitals · October 2026 · React: 9,570 crawled sites · 9,110 with all devices field dataBy Arjen Karel · corewebvitals.io/state-of-cwv
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Lab Total Blocking Time (TBT) per platform

On Wix, 44% of sites use 1 to 200ms TBT lab Total Blocking Time (TBT), and 97% of Wix sites have a good INP, against 95% of all sites. On WordPress, 35% of sites use 1 to 200ms TBT, and 98% of WordPress sites have a good INP.

PlatformLab Total Blocking Time (TBT) on its sitesGood INP
All React sites 9,570 sites1ms to 200ms TBT (Good) 41%0ms TBT (Zero long tasks) 31%201ms to 600ms TBT (Needs Improvement) 14%Over 600ms TBT (Poor) 14%95%
WordPress 2,342 sites1ms to 200ms TBT (Good) 35%Over 600ms TBT (Poor) 26%201ms to 600ms TBT (Needs Improvement) 21%0ms TBT (Zero long tasks) 18%98%
Wix 5,824 sites1ms to 200ms TBT (Good) 44%0ms TBT (Zero long tasks) 37%201ms to 600ms TBT (Needs Improvement) 11%97%
1ms to 200ms TBT (Good) 0ms TBT (Zero long tasks) 201ms to 600ms TBT (Needs Improvement) Over 600ms TBT (Poor)
The State of Web Vitals · October 2026 · React: 9,570 crawled sites · 9,110 with all devices field dataBy Arjen Karel · corewebvitals.io/state-of-cwv
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Total Blocking Time or the platform

Does the platform explain the lab Total Blocking Time (TBT) difference?

On Wix, 98% of sites with 1 to 200ms TBT lab Total Blocking Time (TBT) have a good INP, against 98% of Wix sites with 0ms TBT. Within Wix, sites with 1 to 200ms TBT and 0ms TBT have a good INP about equally often. On WordPress, 99% of sites with 1 to 200ms TBT lab Total Blocking Time (TBT) have a good INP, against 98% of WordPress sites with 0ms TBT. Within WordPress, sites with 1 to 200ms TBT and 0ms TBT have a good INP about equally often.

How lab Total Blocking Time translates into field INP responsiveness

Total Blocking Time sums the blocking portion (anything past 50ms) of every long main-thread task during lab page load. Across 2,989 sites (31.2%) with 0ms TBT and 3,906 sites (40.8%) within 1 to 200ms TBT, 97% and 95% pass field INP (73ms and 80ms median). When lab TBT rises to 201 to 600ms (14.3%), good INP dips to 93% (89ms median), and past 600ms TBT (13.7%, 1,307 sites) good INP falls to 93% (94ms median).

The State of Web Vitals · October 2026 · React: 9,570 crawled sites · 9,110 with all devices field dataBy Arjen Karel · corewebvitals.io/state-of-cwv
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Understanding Total Blocking Time (TBT)

Keep lab Total Blocking Time under 200ms by code-splitting large bundles, deferring non-critical third-party tags until after first interaction, and yielding to the main thread via scheduler.yield() between startup tasks. Across all audited sites, 40.8% sit at 1 to 200ms TBT (95% good INP) while 13.7% exceed 600ms (93% good INP).

Go fix it Yield to the main thread → 14 methods to defer JavaScript → Interaction to Next Paint →
The State of Web Vitals · October 2026 · React: 9,570 crawled sites · 9,110 with all devices field dataBy Arjen Karel · corewebvitals.io/state-of-cwv
Related signals Main-thread CPU (lab) → Lab paint timeline → Document lifecycle (lab) → By Arjen Karel · 9,570 crawled React sites (9,110 with all devices Chrome field data, October 2026) · How we measured