This translation has not been editorially reviewed yet. The German version is authoritative. Deutsche Fassung →
Checking TTFB: how long the server takes to deliver the first byte
Time to First Byte measures how long it takes from the request to the first byte received. It's the lower bound for everything that follows: no content can appear before the server delivers it.
- It includes several stages: name resolution, connection setup, encryption, and the actual processing. Only the last one can be influenced by the application.
- A high value on dynamically generated pages points to database queries or missing caching. A high value on purely static pages points more towards distance to the server or the connection.
- Redirects hit this value hard: every hop is its own server response.
