Good News: The problem still persists
Bad News: The problem still persists
Worse still, it seems this lag will come about on it's own in time. I was just doing farming and making some posts, and FPS dropped from 40 to ~5, and would not go back up until I rebooted wow. I'm going to do some more testing, and maybe try adding a new card to my system tomorrow.
Frustratingly, it seems that the longer WoW stays on, the more it happens. More testing to be done.
UPDATE: Holy crap. I think I found the issue. I was trying to see what RPM my drive was in Speccy... And noticed something about the iGPU. Did some more poking, and saw this:
Sooo yeah. Gonna just bring in a card and turn off the integrated entirely. It's got no fan, and a tiny heatsink. Sort of explains why the previous guy had the side plate off all the time.