Okay, I'll make sure to check out the updated demo.
Edit:
Nope, the update didn't really improve performance for me. MAYBE I get a couple of frames more here and there, but it still dips into the 20s. And even when my PC tells me that I'm playing at 40 FPS it just doesn't feel that way. Might there also be a frame pacing issue?
One thing I haven't mentioned yet: When I'm in the main menu everything is buttery smooth, but I guess that's because that's a static scene in the background?