TTFB or first-byte time simply refers to the time taken by the first byte to reach the client machine when a response is sought from the server after the browser running on it makes an HTTP GET request. Small TTFB values indicate that your web server is fast. Conversely, a high TTFB value signifies that your site is slow in its response to the browser’s HTTP GET request. TTFB occurs as a result of attempts to resolve the address of the site using a DNS in addition to retrieving the response of the first request sent to the site. TTFB occurs in 3 steps, which play significant roles in its duration.

The Time-To-First-Byte Metric

The TTFB is usually divided into three stages, which are composed of multiple steps:

1. Resolving this request by the webserver. During this stage, three values are critical to assess:
   • DNS response time 
   • The distance between the website servers and the end-user
   • Network Stability
2. Submitting the first request to the site address; which requires the following metrics:
   • Physical hardware response time, which is the speed of resolution by the webserver;
   • The current capacity of the server operations; and
   • Network-related latency in the datacenter.
3. Lastly, sending the first response to the end-user, which must take into consideration:
   • The end-users internet speed; and
   • The stability of the network connection.

What is a Good TTFB Value?

Matter of fact, good or bad TTFB varies according to the content of your site. Based on the proportion of the dynamic and static data in your content, what is considered good or bad will definitely vary. On the whole, most speed test tools will offer the following ranges:

• 0 – 75ms Perfect;
• 75 – 200ms Ideal
• 200 – 500ms Less than ideal but acceptable;
• 500ms there is a problem.

But that’s neither here nor there because the fact that the site is entirely composed of dynamic data can lead to an increase in these ranges. The best way to define TTFB is to base the definition of the content of the site.

The Impact of TTFB on Web Performance

Since the first byte is the return period, it is safe to say that TTFB is indirectly related to the performance of subsequent transactions on the web. As such, optimizations to reduce TTFB and facilitate web performance will ensure that your site’s post-TTFB operations will be more efficient. You can execute operations in order to have a “good” TTFB and to create a means for subsequent I/O operations to be faster.

This is especially important for mobile apps where network latency issues due to the fast-changing environmental conditions will greatly impact your TTFB. What this means for you is that the probability of losing users to slow web performance (especially slow pages) is considerably reduced.

The TTFB is something mobile apps developers should take into consideration as most business functions are usually performed on a back-end API. High TTFB values will greatly affect the end-user experience and may lead them to seek faster alternatives. Scanmy.app can test the average TTFB of your on various network conditions and provide helpful tips on improving the effectiveness of your app.