Dan installed OS X Mavericks on his 2009 MacBook Pro and he says he's taken a "speed hit" with a lot of beach balls. Leo says it's best to try and do a clean install to eliminate any rogue fragments of the old OS. If that doesn't fix it, then it may be that the internal drive is starting to get a bit flakey, especially since Dan also booted from a backup external hard drive which worked fine. It may be time to get his data off and replace that hard drive.
Anthony is wondering what will happen for gaming with screens that are surpassing even the retina display resolutions. Leo says that the more resolution there is, the more power it will need to process it. So it makes sense that if there's four times more work, the computer will need more power to push it. Leo says that for gaming, from the perspective of the user, higher resolutions won't necessarily look any better. So it's likely that gaming will stay at 1080p for awhile.