Time to first byte

The time it takes to retrieve the first response byte is the time to first byte. This moment starts the response download. The most important network request is for the document. Once downloaded, the rest of the network resources (images, scripts, style sheets, and so on) can be downloaded.

You can break down the time to first byte process into different steps:

  • Time to create a connection between the browser and server
  • The time it takes to retrieve and possibly render the file on the server
  • The time it takes to send the bytes to the browser

The easiest way to measure time to first byte is by opening the browser developer tools by pressing F12 or Ctrl + Shift + I. Each browser's developer tools have a network tab. Here, ...

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