Maybe it's just something you get used to. I use OSX 95% of the time and the 5% I'm on something else, I think the cursor is too jumpy. I'm sure if I flipped those numbers, I'd think OSX is too delayed.
I don't play FPS games, but it sounds like the lag is a major problem. If Apple has the lag by design, it would make sense for this "feature" to be turned off by default once you start a game, and turned back on once you quit.
Apple has never appeared to be particularly concerned with satisfying the hardcore gamers who tend to play FPS games and who would notice the lag, so this is probably a really low priority for them.
I don't play FPS games, but it sounds like the lag is a major problem. If Apple has the lag by design, it would make sense for this "feature" to be turned off by default once you start a game, and turned back on once you quit.
Apple has never appeared to be particularly concerned with satisfying the hardcore gamers who tend to play FPS games and who would notice the lag, so this is probably a really low priority for them.