Another though with all this talk of latency, etc and suitable motherboards, etc.

How do/did the likes of Fanuc and Heidenhain work? For my use I just want a small PC fitted into the machine, that will just run the cnc control software, a set up the same as Fanuc and Heidenhain.

Is there any latency with Fanuc or Heidenhain controls, and if so anyone know what sort of values?

Not being a particularly computer literate person, if you have a multi core processor, why is it not possible to use one core to just handle the cnc control, and another core to handle the running of the computer?