Claude Core Web Vitals
How real Chrome users experience claude.ai, from Google's Chrome UX Report: the 75th percentile of visits on every device.
Claude fails Core Web Vitals
Sep 26 – Oct 23, all devices
INP
157 ms
Good
LCP
2.7 s
Needs improvement
CLS
0.01
Good
FCP
2.4 s
Needs improvement
TTFB
356 ms
Good
INP over time
Weekly p75. The dashed line is the 200 ms "good" threshold.
What the numbers say
- Claude fails Core Web Vitals on Largest Contentful Paint (2.7 s, good is 2.5 s or less).
- Time to first byte is 356 ms, so most of the LCP time is spent after the first byte: loading the main image, fonts or scripts.
- Among 10 ai sites we track, Claude has the 6th fastest LCP.
- INP has improved by 129 ms over the last 25 weeks, from 287 ms to 158 ms.
Keep a site like this from getting slower
Real-user data shows a regression weeks after it ships. Vitalgate runs Lighthouse on every pull request and fails the check when a change breaks budgets like these: LCP ≤ 2.8 s, CLS ≤ 0.10, FCP ≤ 2.5 s.
Other ai sites
| Site | Core Web Vitals | LCP | INP | CLS |
|---|---|---|---|---|
| OpenAI | Fails | 2.9 s | 219 ms | 0.00 |
| ChatGPT | Fails | 4.2 s | 669 ms | 0.17 |
| Anthropic | Passes | 1.4 s | 67 ms | 0.00 |
| Hugging Face | Passes | 1.1 s | 51 ms | 0.00 |
| Perplexity | Fails | 4.6 s | 353 ms | 0.03 |
| Midjourney | Fails | 2.7 s | 223 ms | 0.00 |
| Mistral AI | Fails | 2.9 s | 101 ms | 0.08 |
| Replicate | Passes | 2.4 s | 73 ms | 0.08 |
| Groq | Passes | 1.1 s | 95 ms | 0.00 |