FYI, for Webpagetest TTFB is the TTFB of the Index request specifically and NOT Webpagetest reported summary First Byte which is a different metric https://community.centminmod.com/threads/cloudflare-automatic-platform-optimization-for-wordpress-cache-effectiveness.20494/
The First Byte summary is a the total for Discovered + DNS + Connect + SSL + TTFB times. The First Byte is the time taken from navigationStart to the browser receiving the very first byte of data from the server. See Matt Hobb’s explanation here.
First Byte summary not same as Index request TTFB
