Time to First Byte (TTFB)

How long the browser waits for the server to start responding.

Good

800 ms or less

Poor

over 1.8 s

What it measures

TTFB covers redirects, DNS, connection setup and server processing. Every other metric starts after it.

Common causes of a poor TTFB

• Pages rendered from scratch on every request.
• Slow database queries or API calls.
• No CDN, so visitors far from the server wait longer.
• Redirect chains.

How to improve it

1. Add full-page caching, ideally at the edge.
2. Put a CDN in front of the site.
3. Profile and fix slow backend code.
4. Link straight to the final URL.