Well I would have to say yes, I have two machines my oldest machine is a mac mini 2011 and it has definitely become a more responsive machine since upgrading, but the best bit is my Mac Book Air a 2012 model. I had bought Black Ops for it when it came out and to say that I was depressed by the performance I received we are talking a game that felt that I was getting 15-30 Frames per second and was not very responsive. After the upgrade of my OS to Mavericks I decided to test BlackOps to see if there are any benefits from the new OS and my initial response would have to be a resounding YES. The game is still sluggish I would think that I’m getting 30-50 FPS now and it definitely is playable. Though not blinding fast it is enjoyable to be able to play this game, I used to play it on a PC with a couple of bad graphics cards, I was getting 30 -50 fps at that time so it feels the same as at that time.
So if you haven't upgraded to Mavericks whats stopping you, I downloaded the Upgrade and ran it with no backups made of my computer and vola two new faster machines.