For posterity's sake, I ran GLXGears on 295.40 and got ~6 FPS again
I downloaded and ran the old 295.33 and ran GLXGears- I got ~1530 FPS.
I then downloaded the patch and applied it to 295.33. Lo and behold: ~1535 FPS with GLXGears.
I apologize for the misinformation earlier. 295.33 with the patch works perfectly. 295.40's security patch is not the cause for the performance degradation.