Time to First Byte (TTFB) is a metric used to determine the responsiveness of a web server. It measures the time between establishing a connection to the server and the start of downloading the content of a web page.
Connecting to a web server is a multi-step process, where each step can potentially cause delays. When a website is slow or unresponsive, accurately identifying the source of the slowdown is key to improving user experience.
TTFB helps organizations identify weak points in the connection process. By determining where delays occur, companies can make changes to deliver their services faster and more reliably. Since website speed can affect search engine rankings, optimizing TTFB performance has become crucial for increasing visibility.
What Influences TTFB?
TTFB is affected by three main actions:
Sending a request from the client machine to the server
Processing the request and generating a response on the server
Sending the response back from the server to the client
Action 1: Sending the request to the server
TTFB measurement starts with the request. The time it takes for a server to receive a request depends on DNS lookup time, the speed of the user’s network, the distance to the server, and any interruptions in the connection. Organizations have no control over the connection between the user and the internet, but any delay here will still affect their TTFB.
Action 2: Processing and generating the response
Once a server receives a request, it must generate a response. This involves initiating processes, making database calls, running web scripts, and communicating with other systems on the network. Common strategies organizations use to reduce TTFB include caching web pages, optimizing server-side code, and improving hardware resources.
Action 3: Sending the response back to the client
After generating the response, the server must send it back to the user. This step depends on both the server’s connection speed and the user’s connection speed. TTFB is officially measured at the moment the client starts receiving the first byte of the response. Transmitting the request and response over the network can account for nearly 40% of the TTFB.