Thanks!
I'm happy that you mentioned the rollercoaster because it was of course one of the example I used a lot when speaking about the game's design!
If you're playing in fullscreen, try perhaps to run the game in windowed mode. I don't know hy but there's a issue with the Unity launcher playing the game in the highest possible resolution, and of course, it may slows it down. Especially because we didn't have enough time to optimise it.
We'll provide a new version were the major bugs are fixed, we're really motivated thanks to all your kind words :)