I suggest not messing with affinity.
Most users finds, after losing lots of time doing tests, that Windows does already a good job of scheduling workload between cores. GSX is already well positioned to take advantage of this, because being run entirely externally from the sim under the Couatl interpreter, it will be marshaller by the OS scheduling automatically so, for example, a long calculation in GSX will not have any effect on the sim performances, since it will always be in another thread, no matter what.
