To take a stab at your performance question...
I've found that CPU is less of a priority than memory, especially if you are running the DB on the same machine as world and zones.
If you are going to run multiple physical servers, an average server with lots of RAM for the DB server and then average servers for world and zone would probably suffice.
Conventional wisdom states that RAM has more effect on DB performance than CPU speed (from my ORACLE days). This is arguably so for MySQL as well.
UberTards, use common sense before flaming me, clearly a 486 with 8Gigs of RAM isn't what I'm talking about.
Regards,
krich