Matt: Hmmm... Can you suggest more things please?
I've deleted some custom forum permissions, maybe ~20-30, and the load is better now.
Okay, if it's your own server, with that kind of load something is very, very wrong. It's hard to tell from the outside what could be causing it, though. If you're the admin of this box, you should be able to tell us, not the other way around. :-)
what plugins are you using, and who is your host?
Server load 131.93?
There may be too many customers on that server.
Oh wait,I'm not sure it's VPS or shared server.
I'm only a forum admin in there.I thought it's VPS. :p
Also,same case like this:
http://community.mybb.com/thread-47057.html & I just searched many case about high server load,too.
When the server load was hight,I tried to close board & disable all plugin.Still same.