It's a bug in the resolution settings!
I reinstalled 14.4.23. I adjusted the resolution settings and it ran smoothly (or at least reasonably so). I closed the game, reopened, back to choppy and sluggish.
Repeated, same problem. Started program, choppy. Adjusted resolution, smooth. Closed and reopened, back to choppy.
Now, it could be just mine (that would suck) but considering the other versions below ran smooth all the time, I think it's a bug in the program.
I'm going to repost in the bug report forum.