Many internal and external factors affect TTFB.
Distance from visitors and origin server
The network connection of the visitor
Installed firewall and other security on the server or WordPress itself
Redirection if any
The network reliability of the DNS provider and registry
Plesk WordPress Toolkit seems very impressive, and cPanel will have this feature soon.
WordPress Toolkit helps to manage multiple WP instances easily. I think we can manage Managed WPs with such tools.
Can we have this type of features in DirectAdmin?