CrUX TTFB(s)

The CrUX TTFB (Time to First Byte) metric measures server responsiveness by tracking how long it takes for the browser to receive the first byte of data from the server. It is retrieved via the CrUX API for a specific origin, with the formFactor based on the user agent used in the crawl. For example, if a mobile user agent is used, the TTFB data will reflect the "phone" formFactor, showing server performance for mobile users

Code: cruxTtfb