Definition
TTFB (Time to First Byte) measures the time between the browser sending an HTTP request and receiving the first byte of the server response. This metric includes DNS resolution time, TLS negotiation for HTTPS connections, and server-side processing (code execution, database queries). Google recommends a TTFB below 800 milliseconds. A high TTFB can be caused by a slow or overloaded server, unoptimized database queries, missing server cache, or hosting geographically distant from the target audience. Using a CDN, implementing application cache (Redis, Memcached), and optimizing SQL queries are the main solutions.
Key Points
- Recommended threshold: below 800 milliseconds
- Includes DNS time, TLS negotiation, and server processing
- Improvable via server cache, CDN, and database query optimization
Practical Examples
Slow shared hosting
A site on shared hosting has 1.8s TTFB. Migration to a VPS with Redis cache reduces TTFB to 200ms.
CDN and TTFB
A French site visited from Asia has 1.2s TTFB. A CDN with Asian points of presence reduces TTFB to 150ms.
Frequently Asked Questions
No, TTFB is a component of LCP but doesn't guarantee it. LCP also depends on resource download and rendering.
Use a CDN, enable server cache (Varnish, Redis), optimize SQL queries, and enable HTTP/2 or HTTP/3.
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Last updated: 2026-02-07