It's more about singe core CPU speed what is limiting the game, not the GPU, so don't just buy a new graphics card and expect miracles.
As for CPUs: Larian have posted on these boards that they had tested a CPU as old as an i5 2400 for a 30 fps minimum. They went with a higher tier CPU on the Intel front in their specs "to be safe". Still a faster CPU than the FX 4350 minimum, mind.
When the OP is talking about bad performance and only being able to play the game at low settings, I had assumed something in the under 30 fps range -- there are guys with i7s and GTX 1060s in the technical forums that reported such frame rates (I think even sub 20 at times), which must have something to do with the systems somehow. Perhaps overheating due to no FPS lock enabled?
