I own a dual socket EVGA SR-2 running Windows.
I know this is the Mac forum, but you may find this helpful.
I was experiencing multiple issues with the game, with no known cause. Ultimately discovered after a full day of troubleshooting that this game does not like symmetric multiprocessing systems (as noted in the FAQ in this forum).
I also discovered I was able to resolve all of these issues at once by disabling one of my CPU sockets using a hardware jumper on the motherboard.
I do not know if dual socket Mac Pros have such a jumper, or perhaps an EFI option, but if they do... its worth a shot for you.
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