The Time To First Byte (TTFB), or server response time, of your WordPress site can be an important indicator of performance. It doesn’t represent the whole picture, but a very specific part in the process.
Time to First Byte is a measure of how fast your server responds when someone tries to visit a page on your site. Specifically, it’s measuring how long it takes from the time the browser asks the server for the page, to when the browser receives the first piece of data from the server.
Visitors want sites to feel fast, so the sooner some meaningful content is displayed on the screen, the better. TTFB can influence this – the faster the server responds, the faster content can get to the user.
There are numerous factors that can affect the server response time of your WordPress site:
- The server’s capabilities and resources.
- The physical distance between the person trying to access the page and your site’s server.
- The size and speed of your WordPress database.
- The performance of the plugins and code on your site.
- The version of PHP your site uses.
- If your site has caching and if the cache is available for that requested page.
- The DNS resolution of your domain.
How to test your TTFB
When you run a speed test on Pingdom, GT Metrix or Webpagetest, look at the length of the first request in the waterfall:
Technically speaking the first request includes the full receiving time of the page’s HTML, whereas TTFB is technically until the start of that receiving section, but the difference between the two measurements should be small.
That’s why you’ll notice on the GT Metrix Timings tab (available if you set up a free account, which is recommended), the TTFB is slightly less than the first request on the waterfall:
Just pick which specific measurement you’re going to use and consistently use that as your benchmark.
There are other tools you can use to measure time to first byte specifically:
In the end, the specific tool doesn’t matter. It’s more important to be consistent with which one you use and take benchmarks so that you can observe any changes after you make optimizations to your site.