A/B testing impact on WordPress sites | The State of Web Vitals 2026

LCP INP CLS

WOWordPress Scoped to 63,295 sites out of 203,892 analyzed (cms) Compare with all sites →

At a glance the headline numbers for A/B testing impact

Performance impact by ab_testing provider.

Providers ranked

After min-sites filter

7,623

Sites in sample

Combined across all items

0.06

Best CLS (p75)

VWO

The State of Web Vitals · October 2026 · WordPress sites (63,295) · desktop field datacorewebvitals.io/state-of-cwv

The ranking sorted by CLS at p75, fastest first

#	Provider	CLS p75	Passing		Sites
1	VWO	0.06	88.2%		92
2	Google Optimize	0.10	75.6%		7,531

The State of Web Vitals · October 2026 · WordPress sites (63,295) · desktop field datacorewebvitals.io/state-of-cwv

Passing CLS per provider which group passes the CLS most often

ProviderSitesPassing CLSp75

VWO 0.1% 92 88% 0.06

Convert 0% 25 86% 0.05

Google Optimize 11.9% 7,531 76% 0.10

LaunchDarkly 0% 18 70% 0.16

Kameleoon 0% 6 67% 0.13

Optimizely 0% 9 25% 0.17

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 · WordPress sites (63,295) · desktop field datacorewebvitals.io/state-of-cwv

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 11.9%

752.5s

9961ms

760.10

672.0s

361.7s

VWO 0.1%

782.4s

9871ms

880.06

692.0s

231.6s

Convert 0%

732.5s

10077ms

860.05

732.1s

461.8s

LaunchDarkly 0%

603.5s

80127ms

700.16

503.1s

442.0s

Optimizely 0%

752.6s

10084ms

250.17

632.2s

501.7s

Kameleoon 0%

832.2s

100106ms

670.13

671.9s

01.7s

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 · WordPress sites (63,295) · desktop field datacorewebvitals.io/state-of-cwv

Related signals Maps (4) → CDN (16) → Chat & messaging (17) → Bot detection (8) → 203,892 crawled sites with Chrome field data, representing millions of real page loads · How we measured

A/B testing impact WordPress sites

At a glance the headline numbers for A/B testing impact

The ranking sorted by CLS at p75, fastest first

Passing CLS per provider which group passes the CLS most often

All five vitals at once the whole category without toggling - cell is the pass rate, small number the p75