phpnuke site taking down the server

I'm rather confused.

Here's the basic info:

Server - Dual Xeon 2.4GhZ
2GB RAM
RHEL 3
cPanel
php_suexec

The site is a phpnuke site with over 7000 members on a shared server. The server load maintains under 1.0 when this site is not active. When we bring the account online and users start going to it again - the load rises quickly to unmanagable levels.

I've optimized the hell out of apache and MySQL. We barely use 50% of the RAM at any time.

What else can I do? I don't think a site like this should be taking down the server...

Thanks...

 

 

 

 

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