Large forum; Optimize search.php

[frankie.]

I have a steady growing forum; http://houstonperformancetrucks.com/

I'm on a dedicated server. My peak hours are 9pm - 12am, I have to log in and turn off message searching due to the search.php file. Everyone clicks on "what's new/ new posts" and it causes a huge load on the forum.

I get loads over 100.00+ if i don't turn off the message searching options.

model name : Intel(R) Celeron(R) CPU 2.00GHz
I'm on 2gb of ram. Just recently upgraded from 1gb ram thinking it was a memory issue. I think the CPU can't handle all of the load, but I want to see if there is a way to optimise the "new posts/whats new" before upgrading to another dedicated server.

Any Ideas? I've followed several articles but none have helped.