via keycdn.com => original post link
There are many reasons why your website may be slow. Time to first byte (TTFB), respectively time to last byte (TTLB), for the initial HTML document is one explanation we want to focus on in this post.
In most cases, we talk about how to optimize our frontend, such as minimizing CSS or compressing images. This is an essential aspect of having a fast loading website, but there are good reasons to optimize the backend. Just imagine that there is a slow database query that delays the page download. Other scenarios are that your origin server reaches its limit due to inefficient code execution and slows down.
What is TTFB?TTFB, which stands for time to first byte, is the amount of time it takes from when a client makes an HTTP request to receiving its first byte of data from the web server. During this period, the following operations take place: