After some experimentation in the beta I have discovered that the one setting in the graphical options that most taxes my i5 and gtx 660 is the terrain shading setting. Both in DX11 and DX12, if I set the terrain shading to low the game runs pretty consistently at a minimum of 30 FPS in the benchmark. I can then get away with upping all of the other settings to either medium or high.

Now my units and weapons fire look beautiful but the terrain looks like someone threw up on it.

I get the feeling that the terrain shaders is the most graphically intensive part of the game. But why? The unit shaders do not have the same impact on performance for one. If anyone has any insights I would love to know! As well as if we can see some optimisation to whatever is causing this in the terrain so that we can up it to medium without, at least in my case, dropping from 30 FPS to 20 FPS.