Our server itself is nothing extraordinary - a Dual Athlon MP 1200, with a gig and a half of RAM - no special SCSI drives, just ordinary 40 GB IDE drives. That said, we have some high performance settings for MySQL - we have it configured to use a large amount of memory, and we are using MySQL 4's new query caching (which, I am sure, is where most of the performance difference is to be found). Also - I'm assuming you tested gforum.cgi - we're running under mod_perl which often shows some improvement - albeit usually quite small - over SpeedyCGI.
Jason Rhinelander
Gossamer Threads
jason@gossamer-threads.com