Skip to main contentHow fast does the banner appear?
240 ms
Median of 15 visits.
All 10 CMPs, best first
- c15t240 ms
- Osano2.15 s
- CookieYes2.42 s
- Cookie Control2.47 s
- iubenda2.66 s
- Enzuzo2.75 s
- OneTrust3.92 s
- Usercentrics4.16 s
- Didomi4.41 s
- Ketch7.95 s
c15tinthc15t cookie banner: speed and features
In our tests, c15t showed its cookie banner in a median 240 ms on an emulated mid-tier phone. It delayed the main content by 408 ms (95% interval 396 ms to 420 ms). Accept responded in 32 ms and Reject in 40 ms. It held trackers back in all 4 consent checks.
On desktop, the banner took 60 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?
+408 ms95% interval 396 ms to 420 ms
Compared with the same page without a consent manager.
All 10 CMPs, best first
- CookieYes176 ms
- c15t408 ms
- Osano424 ms
- OneTrust476 ms
- Cookie Control492 ms
- iubenda612 ms
- Enzuzo768 ms
- Usercentrics844 ms
- Didomi1.28 s
- Ketch1.74 s
How fast does a click respond?
32 msOne visit measured
Reject responded in 40 ms. Under 200 ms feels instant.
All 10 CMPs, best first
- Didomi16 ms
- OneTrust16 ms
- Usercentrics16 ms
- Cookie Control24 ms
- CookieYes24 ms
- c15t32 ms
- iubenda32 ms
- Ketch40 ms
- Enzuzo56 ms
- Osano128 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%
- Usercentrics100%
- Cookie Control75%
- CookieYes75%
- Osano50%
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, mobile (emulated)
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 | 1.55 s | +432 ms95% interval 424 ms to 448 ms | 32 msOne visit measured | 4 of 4 passed |
| React | 1.46 s | +476 ms95% interval 468 ms to 488 ms | 40 msOne visit measured | 4 of 4 passed |
| Next.jsShared with every CMPShown above | 240 ms | +408 ms95% interval 396 ms to 420 ms | 32 msOne visit measured | 4 of 4 passed |
| Nuxt | 240 ms | +512 ms95% interval 504 ms to 524 ms | 32 msOne visit measured | 4 of 4 passed |
| Astro | 251 ms | +328 ms95% interval 324 ms to 332 ms | 32 msOne visit measured | 4 of 4 passed |
| TanStack Start | 250 ms | +416 ms95% interval 408 ms to 436 ms | 48 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 240 ms. The published results do not show when c15t started to load.
| Event | Time from navigation |
|---|---|
| First byte (TTFB) | 21 ms |
| Banner visible | 240 ms |
| First paint (FCP) | 268 ms |
| Consent state known | 1.98 s |
| Largest paint (LCP) | 3.86 s |
| 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 | 21 ms | +15 ms95% interval 10 ms to 26 ms |
| FCPFirst Contentful Paint | 268 ms | +28 ms95% interval 8 ms to 40 ms |
| LCPLargest Contentful Paint | 3.86 s | +408 ms95% interval 396 ms to 420 ms |
| CLSCumulative Layout Shift | 0.00 | No measurable difference95% interval: 0.00 |
| Primary content paintThe page’s main content, not the banner | 3.86 s | +408 ms95% interval 396 ms to 420 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 32 ms.
| Event | Time from the click |
|---|---|
| Screen responds | 32 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 | 66 ms | −1 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 OneTrustc15t’s banner 3.67 s sooner · 1 standard differs
- c15t vs Didomic15t’s banner 4.17 s sooner · 1 standard differs
- c15t vs Cookie Controlc15t’s banner 2.23 s sooner · 1 standard differs
- c15t vs Enzuzoc15t’s banner 2.51 s sooner · 1 standard differs
- c15t vs iubendac15t’s banner 2.42 s sooner · 1 standard differs
- c15t vs Ketchc15t’s banner 7.71 s sooner · 1 standard differs
- c15t vs Osanoc15t’s banner 1.91 s sooner · 1 standard differs
- c15t vs CookieYesc15t’s banner 2.18 s sooner · 1 standard differs
- c15t vs Usercentricsc15t’s banner 3.92 s sooner · 1 standard differs
