I'm sorry but HFS is not an high performance server. It focuses on
usability. Version 2.3 is known for giving better performance, but you said you already tried it.
For the "server down" question, i need to know how to reproduce the problem, so let me know if you find details. In the while, i can suggest to restart the server from time to time, it may solve your problem.
For the expiration of accounts, at the moment is not available, i hope one day it will be available as a plugin for easy installation, since it's already possible to script such feature.