Back in the day I was a software engineer, at a search engine company. Search is hard on large sets of data.
I don't know anything about vBulliten or whatever this site runs on, but I'll bet a dollar that the searches are just standard PHP scripts querying a SQL database. You aren't going to make that scale without some serious hardware. It's the wrong way to go. Way too much data gets pushed through this board.
If anyone here actually has the authority to try and fix search, I'd be willing to give some advice and maybe try to put some software up.
Don't waste your time writing another PHP script.. it's not gonna work. If you REALLY want to fix search, either use this:
http://jakarta.apache.org/lucene/docs/index.html
Or hell, you could probably rig up Google Desktop Search to scan the pages if you exported them to text

That would be a total hack, but it would be a lot faster than a SQL query!
(Ok, don't really do that... Use Lucene.. it's the only way to fly).
Or, hire me! I'll make it work for 10k
