Myself and my friend is doing Co-op(that sounds so bad, sorry I'm kak at english), so not really playing as much. But enjoying it quite a bit, just that in Co-op it doesnt seem like proper co-op, sometimes I see things he can't and vice versa.
Regarding PC performance, Installed the latest GPU drivers(AMD for me, but some nVidia people reported the same) and the performance seems a bit better on PC. That patch did nothing btw.