Wooohoooo!!!! my computer's broken
Well, actually I'm not glad that my computer's broken, but it is, which means that:
1) I wasn't losing my mind.
2) I now what's wrong with it, ergo it can be fixed
that speedfan utility coupled with the alt-tabing tip proved golden. I can actualy see my system heating up just before it begings to lag, at which point I alt-tab out to give it a break, see it cool down, and go back to SH with no problems until it heats up again. (which is pretty darn fast)
I'll try a good clean up job of all my computer first, and see if that helps. If not, I'll follow the advice given for dissipating heat.
I think this will do it, but I'll let you guys know what happens just to share with others on the results.