No, all he, or she, needs to do is set the affinity of that possess - disabling one core is unnecessary.
But KotOR works best with with single core processors. Mine works fine though but for the most part I've found single processors work best.
And that is what setting affinity for a process does - it makes it run on a single core while allowing the rest of the PC to use both cores. As people have said before, please do not recommend things if you have no idea what you are talking about.