I just aquired a popular board, with 3,000-5,000 posts per day, many signups, etc. The problem that I have now is - it uses just way too much CPU/MySQL usage, and even on my own dedicated server - it runs slow!

I know larger sites (such as this one) use some type of mirroring technology. Does anybody have any clue WHAT I should do? Is this done in apache? DNS? Im unsure!

Thanks allot!

Before you do anything talk to someone who is an mysql expert that may be able to optimize mysql for you (or whichever database platform). If your forum is running vBulletin, go to their forums and ask about optimizing mysql. I've seen some members help out with this.

Also, is anything else running on the server?

You should try dedicating a single server for the forum because if you haven't already, there might be stuff running on the server that might be taking up the resources the forum needs.

Last thing - get a second dedicated server and put the mysql database on one server and let apache run on the other.

The best idea would be to setup one server, as the post indicated above, for Apache. Then setup two mysql servers that use mysql replication. Your main goal is redundancy with two mysql servers, but using proper load balancing techniques you can also add an element of speed.

Oh yeah, and I forgot:
Go read Jeremy Zawodny's blog on mysql
http://jeremy.zawodny.com/mysql/

Jeremy is what I would consider an authority on mysql.

I would recommend optimizing the current server's mysql, apache, hard drive ( using hdparm ) to get the best performance out of it.

If that doesn't helps, then you might consider running mysql on another server.

You might also want to install MMTurck cache for php to speed up..