After many hours of fine tunning I can now say I am very happy with how FSX is now running. I wanted to know what the overall thoughts are about the affinity mask setting.  I now have mine at 7 so I am throwing FSX at the first 3 cores leaving core 4 open for add ons. That being said, I have 4 questions and hopefully Good Old Nick will comment as well.

1) Does applying an affinity mask rob horsepower from FSX?

2) If no, is the ONLY MAIN purpose to avoid thread collisions or is there more to it?

3) If running addons ie AI smooth, FDC, ect is it better to apply the mask so core 1 or 4 is open?

4) Which core is best to have closed down in FSX?

Thanks, Jim