TTFB, Protocol and Compression
Three server perf indicators in a single fetch: TTFB, HTTP protocol, Brotli/gzip compression. Quickly detects misconfigured servers.
URL to measure
Measured from a Cloudflare Worker in Europe, a quick approximation, not the true end-browser TTFB.
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Frequently asked questions
What TTFB to target? +
Google considers <800 ms as "good", 800-1800 ms as "needs improvement", >1800 ms as "poor", one of the secondary Core Web Vitals. TTFB depends on the origin server + CDN. Behind Cloudflare with a cache HIT, TTFB drops below 100 ms. Without CDN or with a cache MISS on a slow PHP-FPM, it quickly climbs to 500-1500 ms.
Brotli vs gzip, how much do you gain? +
Brotli compresses 15-25% better than gzip on HTML/CSS/JS. On a 100 KB gzipped page, you save 15-25 KB switching to Brotli, directly visible on mobile latency. All recent browsers support Brotli since 2017. If your server still serves gzip, it is a 2-line config update on Apache/Nginx/Cloudflare.
HTTP/2 vs HTTP/3, practical difference? +
HTTP/2 multiplexes requests over a single TCP connection. HTTP/3 does the same on QUIC (UDP) and survives network changes better (typical WiFi → 4G switch). Noticeable gain on mobile and lost on noisy networks. On Cloudflare, HTTP/3 is one-click. Practically mandatory in 2025.
Why is this not the true browser TTFB? +
The measurement here is from a Cloudflare Worker in Europe. The TTFB a real user experiences also depends on: their network connection (4G vs fiber), geographic distance to the CDN, OS, and DNS lookup. For the "real" TTFB: Search Console > Core Web Vitals (CrUX measurements = actual Chrome users) or PageSpeed Insights. This tool gives a quick approximate measure to pre-flag blatant problems.
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