Why does Virtuamin uses apache in pre-fork as default?
This is awful. Its not 2005 anymore. Most web servers use worker today. Not only it consumes less RAM but allows more traffic to be handled.
Pre-fork cannot scale in traffic.
Based on this, Virtualmin would only be suited for very low traffic websites and servers. Its not fully using the potential from Apache as a web server.
This behaviour should really change in the future. Or in either case, users should have the option when installing it or after it to decide which mode to use.
I searched the forums a bit and its seems you cannot use worker even if you want because it conflicts and creates problems with virtualmin itself.
Honestly, this could be a huge reason not to use Virtualmin. Virtualmin is supposed to be for hosting, to host multiple virtual hosts. But if you are limit into traffic you can handle with Apache it does not make to much sense.