
It’s a little easier when the machine is dedicated to that and only that. The OS doesn’t have all this extra crap running in the background that takes resources from the game because it was designed for that in mind.
At best you’re looking at a 10% performance penalty, closer to the 1-3% range without known bad background software.
I don’t know why he’s making this statement. Blizzard doesn’t make games that don’t nickel and dime you, much less ones people feel are worth paying extra for or even worth their cost.