I really wish that those getting terrible performance on PC would list their CPU, GPU and confirm whether or not they have installed the latest game-ready AMD/Nvidia drivers.
That would help greatly with determining if the PC is simply under-spec or if there's something wrong in the game itself.
We know that at the moment the PC version is very poor with CPU performance, and it could be the root of a lot of problems compared to other PC driving games which don't stress the CPU anywhere near as much.