I've tried all sorts of performance tweaks before, but the best it got was from being always stupidly slow, to being randomly stupidly slow like half the time, and the other half the time just sluggish.
Last night I had the brilliant idea to play around with the page file settings. Today I did most of that, as well as made a few more tweaks.
I set the page file to be a constant size (10 gigs in my case, it's only got 1 gig of RAM), disabled indexing (I end up using things like the find command in cygwin for that anyway since that tends to be faster than using Windows Search), turned off some stuff like various Apple services (I don't own an iWhatever or use iTunes, although I didn't do this before because they never seemed to use much resources), plugged in a 4GB thumb drive for use for ReadyBoost (it came in a pack of 4 for $16, so I had one that no one is using anyway), set Windows to wipe the pagefile on shutdown, and rebooted twice (since I wasn't sure if the pagefile configuration change would happen until I next booted and then shut down).
And holy crap this thing is very much usable now. It's only been a bit so I'll have to see how it goes after a few days of use, but things are *very* promising.
I just thought I'd share in case this helps someone else with a similar problem, even though I don't know which changes specifically helped.