You contacted Feral support? We can see if anything obvious pops up compared to our iMac with the same card.
BTW is that card an official Mac one (EVGA GeForce GTX 680 MAC Edition) or a PC one? We don't support unofficial cards as they can sometimes have strange side effects that only occur in certain circumstances compared to the official "Mac" cards that OS X supports.
I know Washac (who has mentioned issues on his Mac) has a Windows graphics card in his MacPro which seems to have side effects that don't happen when we load the game on Apple supported/shipped card versions. We investigated but it appeared that it was related to the graphics card at the time :'(
Usually unofficial cards just work but we cannot buy all the different PC/Windows cards to test and work around weird side effects so although we try and make sure unofficial cards work (and we don't block them) we cannot guarantee performance or side effects. We often find these cards can work great 99% of the time but then have a problem with a specific area that the reference Apple cards don't.
If you do email support mention you spoke to me on the forums and they will make sure your details get sent over to me to have a look in engineering.
UPDATE: FYI on an 27" iMac with a 680 2GB (2560x1440 and Highest possible settings) I am getting over 30 fps. I had a beta of an upcoming game on max settings tabbed out in the background when I did this test.
Edwin
Bah, that is a 680m too. I just tested Windows 7 in bootcamp on this machine. Same settings and same location in game gives about 85 fps vs the 22 fps I get in 10.9.
This is the eVGA reference GTX 680 flashed with the eVGA for Mac card's ROM. As far as the general consensus goes, it is as close to the Mac card as possible/perhaps exactly the same. I would be grateful if you could have the engineering team take a look my system report anyways. Maybe they do have some insight.
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Are we using the same version? I'm on the Oct 2013 one.
Version 1.9.0 (1) in About OpenGL Driver monitor window.