The performance will depend more on
a) CPU and RAM
b) internet connection speed (MBit/s) and latency (ping times).
This is an ongoing topic. Here are some pointers:
http://moodle.org/mod/forum/discuss.php?d=6920
http://moodle.org/mod/forum/discuss.php?d=25786
Also consider that some of the developers offer specialized hosting services.
Hardware and performance
How much space/bandwidth for 30 teachers?
This discussion has been locked because a year has elapsed since the last post. Please start a new discussion topic.