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Framework

Every CookieBench v3 metric for ten consent managers on Next.js, Desktop profile. One row per metric, one column per consent manager.
Core Web VitalsLCP, CLS and TBT come from the page load. INP comes from the Accept click. Google rates LCP good up to 2.5 s and poor above 4 s. It rates INP good up to 200 ms and poor above 500 ms. It rates CLS good up to 0.1 and poor above 0.25. It does not rate TBT.
Metric	c15t	Cookie Control	CookieYes	iubenda	Didomi	Enzuzo	OneTrust	Osano	Usercentrics	Ketch
LCPLargest Contentful Paint	Good: 148 ms+16 ms vs no CMP	Good: 128 ms	Good: 132 ms	Good: 120 ms	Good: 120 ms	Good: 124 ms+4 ms vs no CMP	Good: 124 ms	Good: 120 ms	Good: 120 ms	Good: 116 ms
INPInteraction to Next Paint, for the Accept click	Good: 16 ms	Good: 16 ms	Good: 16 ms	Good: 16 ms	Good: 16 ms	Good: 24 ms	Good: 24 ms	Good: 32 ms	Good: 16 ms	Good: 40 ms
CLSCumulative Layout Shift	Good: 0.00	Good: 0.00	Good: 0.00	Good: 0.00	Good: 0.00	Good: 0.00	Good: 0.00	Good: 0.00	Good: 0.00	Good: 0.00
TBTTotal Blocking Time during load	0 ms	1 ms+1 ms vs no CMP	0 ms	0 ms	52 ms+52 ms vs no CMP	39 ms+39 ms vs no CMP	1 ms+1 ms vs no CMP	1 ms+1 ms vs no CMP	50 ms+50 ms vs no CMP	172 ms+172 ms vs no CMP
Page loadGoogle rates TTFB good up to 0.8 s and FCP good up to 1.8 s. Content paint is the paint time of the article image. We time it even when the banner was the largest element.
TTFBTime to First Byte	Good: 22 ms+17 ms vs no CMP	Good: 6 ms	Good: 8 ms	Good: 6 ms	Good: 6 ms	Good: 6 ms+0 ms vs no CMP	Good: 6 ms	Good: 6 ms	Good: 5 ms	Good: 5 ms−0 ms vs no CMP
FCPFirst Contentful Paint	Good: 92 ms+28 ms vs no CMP	Good: 64 ms	Good: 64 ms	Good: 64 ms	Good: 68 ms	Good: 64 ms	Good: 60 ms	Good: 68 ms	Good: 64 ms	Good: 60 ms−4 ms vs no CMP
Content paintThe article image painted	148 ms+16 ms vs no CMP	128 ms	132 ms	120 ms	120 ms	124 ms+4 ms vs no CMP	124 ms	120 ms	120 ms	116 ms
LCP elementWhat the browser picked as the largest element
BannerMilliseconds from navigation. p75 is where the slowest quarter of visits starts.
CMP requestedFirst request for the CMP’s script or config
CMP loadedThe download of the CMP’s main script is complete
Consent knownThe CMP reports the visitor’s consent state	166 ms
Banner visibleThe banner is on screen	60 ms	385 ms	387 ms	431 ms	466 ms	477 ms	629 ms	644 ms	672 ms	1.68 s
Screen coveredShare of the viewport the banner covers
Click responseTime until the screen updates. We rate it like INP: good up to 200 ms, poor above 500 ms. The browser reports these times in 8 ms steps. It does not report clicks under 16 ms.
AcceptAccept all, from the banner	Good: 16 ms	Good: 16 ms	Good: 16 ms	Good: 16 ms	Good: 16 ms	Good: 24 ms	Good: 24 ms	Good: 32 ms	Good: 16 ms	Good: 40 ms
RejectReject all, from the banner	Good: 16 ms	Good: 24 ms	Good: 16 ms	Good: 16 ms	Good: 16 ms	Good: 16 ms	Good: 24 ms	Good: 24 ms	Good: 16 ms	Good: 16 ms
SaveSave, in the preferences dialog	Good: 24 ms			Good: 32 ms	Good: 40 ms	Good: 16 ms	Good: 32 ms	Good: 48 ms	Good: 16 ms	Good: 16 ms
Next clickA click on the page 500 ms after Accept	Good: 16 ms	Good: 16 ms	Good: 16 ms	Good: 16 ms	Good: 16 ms	Good: 16 ms	Good: 16 ms	Good: 16 ms	Good: 16 ms	Good: 16 ms
After AcceptMilliseconds from the click. Main thread is the long-task blocking time after it.
Banner goneBanner and any overlay removed
Consent appliedThe CMP’s consent state matches the choice
Scripts ranEvery script that the choice lets run is complete
Main threadLong-task blocking time after the click
After RejectReject lets no scripts run, so there is no script time to report.
Banner goneBanner and any overlay removed
Consent appliedThe CMP’s consent state matches the choice
Main threadLong-task blocking time after the click
After SaveFrom the Save click in the preferences dialog.
Banner goneBanner and any overlay removed
Consent appliedThe CMP’s consent state matches the choice
Scripts ranEvery script that the choice lets run is complete
Main threadLong-task blocking time after the click
Download sizeThe first load. Unpacked is the size after decompression. That is the code that the browser must parse.
TransferredBytes over the network during the first load	725 KB+112 KB vs no CMP	712 KB+99 KB vs no CMP	644 KB+31 KB vs no CMP	735 KB+122 KB vs no CMP	866 KB+253 KB vs no CMP	766 KB+153 KB vs no CMP	824 KB+211 KB vs no CMP	700 KB+87 KB vs no CMP	777 KB+164 KB vs no CMP	1.15 MB+532 KB vs no CMP
UnpackedThe same bytes after decompression	1.45 MB+472 KB vs no CMP	1.32 MB+346 KB vs no CMP	1.07 MB+98 KB vs no CMP	1.44 MB+458 KB vs no CMP	1.98 MB+1.00 MB vs no CMP	1.57 MB+592 KB vs no CMP	1.83 MB+855 KB vs no CMP	1.33 MB+348 KB vs no CMP	1.69 MB+711 KB vs no CMP	8.18 MB+7.20 MB vs no CMP
DeferredBytes transferred after the first load settled
RequestsRequests during the first load	16+6 vs no CMP	12+2 vs no CMP	19+9 vs no CMP	14+4 vs no CMP	16+6 vs no CMP	12+2 vs no CMP	22+12 vs no CMP	14+4 vs no CMP	27+17 vs no CMP	19+9 vs no CMP
Third-partyRequests to other hosts during the first load	0	2	9	4	6	2	12	4	17	9
Returning visitorsA visitor who accepted earlier loads the page again. We expect the banner to stay hidden.
Banner hiddenThe banner stayed hidden on the return visit
Consent knownTime from navigation until the CMP restores the stored choice
Consent checksNo tracker or cookie before the visitor chooses, and the choice holds afterwards. A check we could not run is not a failure.
ChecksLoad, Accept, Reject, Save, withdrawal and keyboard checks	4 of 4 passed	3 of 4 passed1 could not run	3 of 4 passed1 could not run	4 of 4 passed	4 of 4 passed	4 of 4 passed	4 of 4 passed	4 of 4 passed	4 of 4 passed	4 of 4 passed

A value without a “vs no CMP” line had no measurable change from the same page without a consent manager.