1
At a glance the headline numbers for A/B testing impact
Performance impact by ab_testing provider.
1
Providers ranked
After min-sites filter
745
Sites in sample
Combined across all items
0.02
Best CLS (p75)
Google Optimize
The State of Web Vitals · October 2026 · React sites (9,570) · phone field datacorewebvitals.io/state-of-cwv
2
The ranking sorted by CLS at p75, fastest first
| # | Provider | CLS p75 | Passing | Sites | |
|---|---|---|---|---|---|
| 1 | Google Optimize | 0.02 | 90.6% | 745 |
The State of Web Vitals · October 2026 · React sites (9,570) · phone field datacorewebvitals.io/state-of-cwv
3
Passing CLS per provider which group passes the CLS most often
ProviderSitesPassing CLSp75
Optimizely 0.2% 19 0.07
Google Optimize 7.8% 745 0.02
Kameleoon 0.1% 7 0.03
VWO 0.1% 14 0.04
Convert 0.1% 6 0.20
LaunchDarkly 0.1% 9 0.42
Good Needs Improvement Poor Sorted best-passing first · median colored by its own rating · pass = good CLS (0.1 at p75) · one value per site
The State of Web Vitals · October 2026 · React sites (9,570) · phone field datacorewebvitals.io/state-of-cwv
4
All five vitals at once the whole category without toggling - cell is the pass rate, small number the p75
LCP
INP
CLS
FCP
TTFB
Google Optimize 7.8%
782.3s
91139ms
910.02
741.8s
581.3s
Optimizely 0.2%
772.2s
63217ms
940.07
592.0s
291.2s
VWO 0.1%
692.5s
77195ms
850.04
851.7s
62942ms
LaunchDarkly 0.1%
05.6s
33563ms
330.42
03.2s
02.0s
Kameleoon 0.1%
862.2s
86176ms
860.03
572.0s
431.5s
Convert 0.1%
503.4s
100157ms
500.20
672.7s
331.6s
60%95%+ passing Cell: pass rate, small number = p75 · faded rows: under 100 sites
One row per provider, one column per vital - the cell is the share of sites passing, the small number the p75. No toggling needed to see where the category actually differs.
The State of Web Vitals · October 2026 · React sites (9,570) · phone field datacorewebvitals.io/state-of-cwv
Related signals Maps (4) → CDN (16) → Chat & messaging (17) → Bot detection (8) → 210,902 crawled sites with Chrome field data, representing millions of real page loads · How we measured
210,902 crawled sites with Chrome field data, representing millions of real page loads. How we measured.