I'm running CrunchBang Waldorf with OpenBox on a Lenovo e420. I made the switch from Windows a few months ago, and have had no problems with performance since then. Everything runs nice & fast.
Today I was geeking around experimenting with some new options for my work setup. I installed XFCE, logged in from SLiM & played around with it a bit. Returned to OpenBox, and messed with a new terminal emulator (rxvt-Unicode). I played around with the command line options to see what visual appearance I liked.
At some point after doing this for a while, terminal windows started loading slowly. I used ARandR to switch to a dual-screen setup, and at that point the system slowed to a crawl for several minutes. This has never happened before.
I had configured my rxvt windows to open with the Fish shell, and also played around with transparency effects, so I figure any of several factors could have caused the slow performance: transparency, something new XFCE installed without my knowledge, Fish, etc. (Frankly though, none of those programs ought to cause that kind of slowdown... right?)
The long story short is, if this happens in the future, how would I go about tracking it down? Any tips? I am hoping there is some logfile that will tell me what background processes were run at what times in say the last thirty minutes.