Nice track but still need some improvements to make it great.
I have tried the mid layout, it is a bit too rough IMHO, some parts are visually and, most importantly, physically too polygonal, we can feel the seams of the polygons.
Also, from pure racing point of view, turn signs would be very welcome, as on my quite small 17" screen, it's not that easy to distinguish gray walls in front of a 90% turn fast enough.
Maybe some cones or tyre walls for instance.
Regarding FPS, I get some slowdown when some buildings/objects get into view (I have a GeForce 780M GTX)
Release somewhere in Spring(-ish)