I have a late 2013 iMac that I just purchased a few months ago which has the GeForce 750m graphics card. Since upgrading to El Captain, like many of you, my graphics performance has taken a nose dive. Nvidia did release an El Captain update, but not for this chipset. I have an older backup on Yosemite, back when my system was smooth as butter, and I wouldn't lose that much data. Is it worth reverting back to Yosemite, or will El Captain have its bugs worked out soon?