Using too much of server load with shared host

[mme42]

We've been told by our shared server host that we are creating too much server load. They said it's php and mysql processes from us that's keeping the load high...mainly php.

I realize that a lot of hosts oversell shared hosting, and maybe they are just trying to get us to upgrade. We haven't ruled out that stuff. But, they said if we can get our server usage down, we can stay. So I want to try everything I can. We don't really have the money to go vps or dedicated yet. And a few admins of other sites have said that it doesn't seem right that we should be responsible for so much of the load. So it seems that either there is something fundamentally wrong with our forum causing more server load than it should, or the host is pulling a fast one on us.

I've gone through and shut off most of our plugins/products/mods. I've changed some vb settings to optimize. It didn't seem to have any effect on the server load. I realize that the server load that shows in the admin cp is the load for all the sites hosted on our shared server. But, since they told us that it was us using nearly all of the resources, I figured if I fixed it, I'd see some kind of drop. Either I didn't fix it (likely, haha) or they were lying.

A couple questions:

1. How can I tell how much of the server load is because of us?
2. How can I find what specific processes are problematic
3. Any good links on optimizing vb, mysql, etc? (I realize that's probably broad, but a place to start would be nice)
4. How can I find out how many other sites are hosted on our server? I tried a reverse IP search (myIPneighbors.com) but it only listed our site.
5. Any ideas on what to do next?

About our forum:

* vBulletin 3.8.1
* Intel Xeon CPU 3065 @ 2.33GHz
* Total memory: 4148904 kB (Free: 179680kB)
* Linux / litespeed
* PHP 5.2.6
* MySQL 5.0.37-standard
* Direct Admin 1.33.6
* Most if not all products/mods temporarily disabled
* Currently active users 238 (41 members and 197 guests)
* Server load 2.91 2.48 2.48 (sometimes gets up to 5 during peak times)
* If anything else is needed, let me know.


Thanks for any ideas.

[Dismounted]

Ask them which script(s) specifically are causing the load.