A friend of mine has a site built around phpfusion that I do a little dev work on from time to time. The site is on it's own dedicated server and at first did well, however of late it's been lagging a little. Checking the server during lag times shows mySQL taking over most of the CPU usage, but the number of users online at that time isn't extraordinary.

I suspect there's some bad query code in there somewhere, but I'm not sure how to proceed from here in determining what's causing the hangups. Any suggestions?

Jamie, I think it would be best to benchmark and time the amount of time it takes for each query in order to determine which is the slowest. However, what is PHPFusion? I can't recommend any tools because I do not know what it is. A simple way to perform query timing is to record the time before and after the query if you do not have access to better benchmarking tools.