Skip to main contentHow fast does the banner appear?
60 ms
Median of 15 visits.
All 10 CMPs, best first
- c15t60 ms
- Cookie Control385 ms
- CookieYes387 ms
- iubenda431 ms
- Didomi466 ms
- Enzuzo477 ms
- OneTrust629 ms
- Osano644 ms
- Usercentrics672 ms
- Ketch1.68 s
c15tinthc15t cookie banner: speed and features
In our tests, c15t showed its cookie banner in a median 60 ms on desktop. It delayed the main content by 16 ms (95% interval 8 ms to 40 ms). Accept responded in 16 ms and Reject in 16 ms. It held trackers back in all 4 consent checks.
On an emulated mid-tier phone, the banner took 240 ms. Per vendor docs, c15t supports IAB TCF, IAB GPP, Google Consent Mode v2 and Global Privacy Control, but not Google CMP certification.
How fast is c15t’s cookie banner?
Does it slow the page down?
+16 ms95% interval 8 ms to 40 ms
Compared with the same page without a consent manager.
All 10 CMPs, best first
- Didomi−4 ms
- iubenda−4 ms
- CookieYes−4 ms
- Ketch0 ms
- Osano0 ms
- Usercentrics0 ms
- Enzuzo4 ms
- OneTrust4 ms
- Cookie Control8 ms
- c15t16 ms
How fast does a click respond?
16 msOne visit measured
Reject responded in 16 ms. Under 200 ms feels instant.
All 10 CMPs, best first
- c15t16 ms
- Cookie Control16 ms
- Didomi16 ms
- iubenda16 ms
- Usercentrics16 ms
- CookieYes16 ms
- Enzuzo24 ms
- OneTrust24 ms
- Osano32 ms
- Ketch40 ms
Does it block trackers until consent?
4 of 4consent checks passed
No tracker ran and the page set no cookie before the visitor chose.
All 10 CMPs, best first
- c15t100%
- Didomi100%
- Enzuzo100%
- iubenda100%
- Ketch100%
- OneTrust100%
- Osano100%
- Usercentrics100%
- Cookie Control75%
- CookieYes75%
Which standards and features does c15t support?
Each status comes from inth’s documentation for c15t. CookieBench does not test these features unless a line says so.
- Verified by test
- Per vendor docs
- Partial
- Not supported
- Unknown
| Feature | Status |
|---|---|
| IAB TCF | Per vendor docs (vendor documentation, opens in a new tab) |
| IAB GPP | GPP 1.1 (vendor documentation, opens in a new tab) |
| Google Consent Mode v2 | Per vendor docs (vendor documentation, opens in a new tab) |
| Google-certified CMP | Not on Google’s list (vendor documentation, opens in a new tab) |
| Global Privacy Control | Per vendor docs (vendor documentation, opens in a new tab) |
| Feature | Status |
|---|---|
| Geo-targeted banners | Per vendor docs (vendor documentation, opens in a new tab) |
| Script blocking | Per vendor docs (vendor documentation, opens in a new tab) |
| Consent records | With a backend (vendor documentation, opens in a new tab) |
| Cookie scanning | Via Inth Website Audit (vendor documentation, opens in a new tab) |
| Feature | Status |
|---|---|
| Open source | Apache-2.0 (vendor documentation, opens in a new tab) |
| Self-hostable | Per vendor docs (vendor documentation, opens in a new tab) |
| Headless UI | Per vendor docs (vendor documentation, opens in a new tab) |
| TypeScript types | Per vendor docs (vendor documentation, opens in a new tab) |
| Feature | Status |
|---|---|
| Free tier | Open source; hosted free plan (vendor documentation, opens in a new tab) |
Which frameworks does c15t support?
- First-party SDKs
- React, Next.js, Vue, Nuxt, Svelte, SvelteKit, Astro and TanStack Start
- Script tag
- Supported
- Measured in this run
- Script tag, React, Next.js, Nuxt, Astro and TanStack Start
- SDKs not measured yet
- Vue, Svelte and SvelteKit
Support per inth’s documentation.
c15t’s results by framework, desktop
Each row is a separate app. We measured each one against the same app without a consent manager. The rows compare integrations, not frameworks.
| Framework | Banner appears | Page slowed by | Click responds in | Trackers blocked |
|---|---|---|---|---|
| Script tag | 267 ms | No measurable delay95% interval −8 ms to 24 ms | 16 msOne visit measured | 4 of 4 passed |
| React | 332 ms | +36 ms95% interval 28 ms to 52 ms | 16 msOne visit measured | 4 of 4 passed |
| Next.jsShared with every CMPShown above | 60 ms | +16 ms95% interval 8 ms to 40 ms | 16 msOne visit measured | 4 of 4 passed |
| Nuxt | 45 ms | +64 ms95% interval 36 ms to 84 ms | 24 msOne visit measured | 4 of 4 passed |
| Astro | 38 ms | +36 ms95% interval 20 ms to 48 ms | Under 16 msOne visit measured | 4 of 4 passed |
| TanStack Start | 54 ms | +24 ms95% interval 8 ms to 44 ms | 16 msOne visit measured | 4 of 4 passed |
Were there problems testing c15t?
We show each missing answer as missing, never as zero.
Desktop
- c15t makes this route render per request, while the no-CMP page is prerendered. That accounts for most of its added TTFB and FCP.
Mobile (emulated)
- c15t makes this route render per request, while the no-CMP page is prerendered. That accounts for most of its added TTFB and FCP.
When does c15t load, and what does it cost the page?
Lab detail for engineers. All Core Web Vitals are here. The summary leaves some of them out.
When does c15t start loading?
The banner was visible at 60 ms. The published results do not show when c15t started to load.
| Event | Time from navigation |
|---|---|
| First byte (TTFB) | 22 ms |
| Banner visible | 60 ms |
| First paint (FCP) | 92 ms |
| Largest paint (LCP) | 148 ms |
| Consent state known | 166 ms |
| CMP requested | |
| CMP loaded |
How do page vitals compare with no consent manager?
Each row shows the value on the page with the consent manager. It also shows how far the value moved from the same page without one.
| Measure | With c15t | Difference |
|---|---|---|
| TTFBTime to first byte | 22 ms | +17 ms95% interval 8 ms to 23 ms |
| FCPFirst Contentful Paint | 92 ms | +28 ms95% interval 8 ms to 52 ms |
| LCPLargest Contentful Paint | 148 ms | +16 ms95% interval 8 ms to 40 ms |
| CLSCumulative Layout Shift | 0.00 | No measurable difference95% interval: 0.00 |
| Primary content paintThe page’s main content, not the banner | 148 ms | +16 ms95% interval 8 ms to 40 ms |
What was the largest element on screen?
LCP times the largest element on screen. If that is the banner, LCP measures the banner instead of the page.
There is no LCP attribution for this profile and framework.
What happens after a visitor clicks Accept?
The screen responded to Accept in 16 ms.
| Event | Time from the click |
|---|---|
| Screen responds | 16 ms |
| Banner gone | |
| Consent applied | |
| Analytics active |
How much does it download?
Initial transfer happens before the page settles. Deferred transfer comes after.
| Measure | With c15t | Difference |
|---|---|---|
| Initial transferBytes before the page settles | 725 KB | +112 KB95% interval: 112 KB |
| Deferred transferBytes loaded later | Not compared | |
| RequestsAll requests | 16 | +6No interval reported |
| Third-party requestsRequests to other hosts | 0 | 0No interval reported |
Does it block the main thread?
Long tasks are stretches over 50 ms when the page cannot respond to taps or keys.
| Measure | With c15t | Difference |
|---|---|---|
| Long-task timeBlocking time during load | 0 ms | 0 msNo interval reported |
What do returning visitors see?
A visitor who accepted on an earlier visit comes back. We check that the banner stays hidden.
- Banner stayed hidden
- Consent state known at
What was tested?
- Methodology
- cookiebench-v3.2.4
- Analysis
matrix-2026-10-11
On desktop, it appeared in a median 60 ms, against 471 ms for the median of the 10 CMPs measured. On an emulated mid-tier phone, it appeared in a median 240 ms, against 2.71 s for the median of the 10 CMPs measured.
On desktop it delayed the main content by 16 ms (95% interval 8 ms to 40 ms). On an emulated mid-tier phone it delayed the main content by 408 ms (95% interval 396 ms to 420 ms). Delay is the extra time before the main content appears. We compare Largest Contentful Paint on the same page, with and without a consent manager.
It passed 4 of 4 checks on desktop and on an emulated mid-tier phone. A check fails if a tracker runs, the page sets a cookie or data leaves the page before the visitor chooses.
Per vendor docs, c15t supports IAB TCF, IAB GPP, Google Consent Mode v2 and Global Privacy Control, but not Google CMP certification. Feature support comes from c15t’s documentation. CookieBench did not test these features itself.
Compare c15t with…
- c15t vs OneTrustOn desktop, c15t showed its banner in a median 65 ms, against 672 ms for OneTrust.
- c15t vs Didomic15t’s banner 406 ms sooner · 1 standard differs
- c15t vs Cookie Controlc15t’s banner 325 ms sooner · 1 standard differs
- c15t vs Enzuzoc15t’s banner 417 ms sooner · 1 standard differs
- c15t vs iubendac15t’s banner 371 ms sooner · 1 standard differs
- c15t vs Ketchc15t’s banner 1.62 s sooner · 1 standard differs
- c15t vs Osanoc15t’s banner 584 ms sooner · 1 standard differs
- c15t vs CookieYesc15t’s banner 327 ms sooner · 1 standard differs
- c15t vs Usercentricsc15t’s banner 612 ms sooner · 1 standard differs
