On my machine it runs quite smoothly:
- Intel i7 4770K 4x3.5 GHz (+Hyperthreading)
- AMD Radeon HD7850
- enough RAM (shouldn't be a problem anyway)

My CPU is probably above average but I think my GPU should be quite a bit worse than what most people (gamers) have nowadays.

I didn't play the demo for very long, yet, but this is what I noticed:

> the input seems a bit laggy, might be vsync, delay caused by windowed mode or it's engine related
> like in superku's demo, there still is mouse_force.xy used for the camera's rotation.
I highly recommend you to use mickey.xy instead. This one doesn't cap at ±1.
The values are a lot higher, though, so you have to scale it down a bit.