I actually have a major performance gain by making sure nwmain.exe is utilizing multiple cores. "Client CPU Affinity=0" Assures that it only uses your first core - if you want it to use all available cores, you want "Client CPU Affinity=-2" to disable that option. Big FPS boost for me.
Also, side note, nwtoolset.exe also has a similar option, and the toolset runs MUCH faster with a value of -2.