Hey everyone - we're aware of some issues introduced in Game Update 1.4 that may cause frame stuttering or performance problems (particularly on CrossFire or SLi setups). If you are experiencing these problems, please try disabling shadows. We are working on resolving these issues, but disabling shadows in the meantime may result in a performance increase. If you notice a performance increase after disabling shadows, please post to let us know (as some of you already have). We'll update you if we have any more information to share as we work on this issue. Thank you!
Tried that. Didn't really help. The only fix was disabling CrossFire entirely.
Framerate improved somewhat, but still a ton of stuttering and still utterly unplayable.