Performance

Network time (connectEnd – fetchStart)
How long it takes to connect to server. This includes the time needed to lookup DNS and establish a TCP connection. This value might be 0 after the first request to a domain as the browser might cache the connection.

Server time (responseStart – requestStart)
How long it takes the server to generate page. This is the time between the server receiving the request and starting to serve the response.

Transfer time (responseEnd – responseStart)
How long it takes the browser to download the response from the server. Technically speaking, this is the time between receiving the first byte until the response is complete.

DOM Processing time (domInteractive – domLoading)
How long the browser spends loading the webpage after the response has been fully received and until the user can start interacting with it.

DOM Completion time (domComplete – domInteractive)
How long it takes for the browser to load images/videos and execute any Javascript code listening for the DOMContentLoaded event after the webpage has loaded and a user can already interact with it.

On load time (loadEventEnd – loadEventStart)
How long it takes for the browser to execute Javascript code waiting for the window.load event (when the DOM was completely rendered).

Page load time
How long it takes to load the whole page, from requesting a page until it is fully rendered within the browser. This is the sum of all previous metrics. If you only track one metric this is it! We recommend you aim to keep this under 2 seconds where possible.