Akito He has posted in this discussion, just scroll up...
TTFB can be impacted by many things, to name a few:
- use a later php version, 8.0 and later is much faster than previous versions
- use opcache
- disable xdebug
- reduce latency between database server and the webserver (some shared hosting provider make use of an off-server database cluster, which improves availability, but increases latency)
- optimize your database server
- optimize your webserver and php handling; apache, nginx, fpm etc they all have to be configured related to the resources available
- reduce the number of installed extensions; or test performance with randomly disabled extensions to pinpoint a possible cause for badly performing extensions
- ttfb can also be impacted by dns or network; think about loadbalancers, cloudflare or nameservers.
