Finding out where the slowdown is coming from?
 

My forum is experience intermittent slowdowns during the day and I'd love to know where they are coming from. It doesn't even seem to be at busy times, loads just spike at different times throughout the day. How could I determine what is causing these load spikes? Are there ways to determine what kind of load any plugins are putting on it besides disabling all of them and enabling one by one?

Are you on a shared server? If so, the load spikes may have nothing to do with your site at all since the load is for the whole server and could be caused by another site sharing the same server.

I'm on a dedicated and have full access to the server. No other sites run on the server.

Do you have any clue of what is slowing the machine down? Does CPU load spike? Does RAM usage spike?

Not really. CPU usage spikes, but RAM stays the same most of the time.

That's a step forward. :) When CPU usage is spiking, have you run top to see which process is taking up the cycles?

Not really, I'm not on the forum or the server all the time. I just get reports from my members that they are being kicked off. Logs confirm that loads are high. I'm sure if I were on it, it would just inform me that apache, mysql, or PHP is the process causing the high load, but that doesn't really tell me much at all.

Start by posting a server tuning request on vB.com.

Yeah, I've looked at those threads before. I've tuned my server some. This, however, is not really a case of server tuning, as much as it's a hunt for what is using my resources. I could have the server tuned to the best of it's ability, but if I have a plugin making 20 mysql calls per page, then I doubt it would help much.

Which would further narrow down what is actually holding up the server. It may well be some small Apache config setting, you never know.