TTFB is the time from a request being sent until the first byte of the response arrives. It captures DNS, connection, TLS and server processing time, and it sets the ceiling for how fast your page can possibly load.
Time To First Byte measures everything that happens before content starts arriving. A high TTFB delays rendering and worsens Core Web Vitals no matter how optimised your front end is.
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For business owners
TTFB is the invisible head start (or handicap) every page load begins with. If your server takes a second to send the first byte, the user waits a second before anything can happen. Reducing it makes the entire site feel snappier and improves the metrics search engines and customers care about.
How it works (technical)
TTFB decomposes into: DNS lookup, TCP connection, TLS handshake, request send, server processing, and time to first response byte. The largest lever is usually server processing (caching and query optimisation), followed by network/geography (a CDN reduces round-trip distance) and connection setup (HTTP/2, HTTP/3, TLS 1.3 and connection reuse). Aim for under ~200ms for cached responses.
Real-world example
An international audience experienced slow first loads because the server sat in one country and TLS setup added round trips across the ocean. Fronting the site with a global CDN and enabling TLS 1.3 cut TTFB for distant users by more than half.
Why it matters
TTFB gates every downstream metric including LCP. Scanners and performance tools report it because it isolates server and network speed from front-end concerns.
How to fix it
Cache responses so the server does minimal work per request.
Use a CDN to shorten the network distance to users.
Enable HTTP/2 or HTTP/3 and TLS 1.3 to reduce connection overhead.
Optimise back-end code and database queries.
Keep connections warm and reuse them where possible.
Best practices
Measure TTFB from the regions your users are actually in.
Serve cacheable content from the edge.
Separate server time from network time when diagnosing.
Common mistakes
Ignoring TTFB and optimising only images and scripts.
Serving a global audience from a single distant origin.
Leaving TLS on older, slower versions.
Frequently asked questions
Is TTFB a Core Web Vital?
No, but it directly influences LCP, which is. A poor TTFB makes good Core Web Vitals much harder to achieve.
Put this into practice
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