Definition:
Time to first byte (TTFB) is the total time spent by the remote server to send the first byte of data after a user requests the data or webpage. TTFB is technical jargon used primarily to define or measure the responsiveness or speed of a remote website or web server.
Time To First Byte Measurement
The time to the first byte is measured by adding the total time it takes for the browser to receive the first byte of the requested page. This time starts when the user types into a website or the IP address of the server and asks to go there. Time stops on TTFB once the first byte of information comes back to the browser. A high-response server, with a good network, will have a lower TTFB time; the TTFB will be higher for a low-end server with limited bandwidth.
Time to the optimal first byte
According to Google, the time to the first byte of a website should be 200 milliseconds or less. If a site is much slower, for example, 500 milliseconds or more, some work is needed on it. Typical good speeds for the TTFB could be 100 milliseconds for static content (content that already exists on the server as files) or between 200 and 500 milliseconds for dynamic content (content that joins a database and templates, such as WordPress).
There are four causes of TTFB being slow:
- Web traffic is high.
- Network problems.
- Dynamic content: disk usage, disk speed, RAM usage, database configuration, database speed…
- Server configuration: PHP/ASP configuration, database properties, if the server is shared…