[snakes1100]

That server should handle far many users than that at one time, from the looks of your post over at vb.com, did you ever setup xcache right?

You was also right, there was numerous posting about xcache & php, it was actually a memory leakage issue though for certain distros. Im running 5.2.6, but then again i run gentoo on numerous servers i administrate.

You going to have to get dirty and start with enabling logging in mysql for slow & non indexed queries, turn on debug as well in apache and see what it spits out in the log.

Make sure you have xcache setup right.

Make sure your not running out of ram and swapping

Make sure you have apache setup right to serve the visitors and not bloat it with to many start servers, min, max etc, i also note george told you to turn on keepalive, i would disagree with him on that for large sites, it would be better to keep it off or turn down the timeout to 1, 2 at the most. I'd also upgrade apache to 2.2.8 and get rid of 1.3.xx

I would also dump off searching to MySQL and take it out of vb's hands.

Without looking at the server live, there is not much any of us can do but make suggestions to you.