Diagnose periodic slowdowns/freezes When I am watching a YouTube video, the video will pause and freeze for about one second, every 10 seconds on the dot. I've timed it. I have also tried watching activity monitor but it doesn't show anything out of the ordinary spiking. And it's not Flash or the browser in particular, though they show the worst effect. But even as I type this, every 10 seconds it freezes. In other programs too I'm pretty sure I have seen this freeze. (lately I haven't used many other programs, to be honest, so I'm not 100% sure)

I am trying to avoid the brute force approach of removing things one by one and seeing if it stops. Before I resort to that, is there anything sort of like activity monitor but maybe that will graph usage so I can just look at a spike in usage from a single process? Or is there some other method you can recommend for finding out what is causing this every-10-second freeze?

This, by the way, is a few-month-old 17" MacBook Pro with a 2.8ghz i7 and 4gb of RAM and all updates.
Sometimes a good place to look is the syslog.  If you know it's every 10 seconds then there's a chance that a message will get logged for whatever is happening.  Try this in terminal and append the results to your question or even have a look yourself for anything that looks unusual which is happening on 10 second intervals.

tail -n 20 /var/log/system.log  

You need to be an admin user to run the above command