The issues are also causing internal temperatures to skyrocket. One forum user showed how playing a 4-minute track in iTunes caused the internal temperature of his Mac Pro to increase by 11 degrees.
Several users have shown that booting into Windows 7 on the Mac Pro resolves these issues, pointing the finger at OS X as causing the problem.
Forum members are saying that pleas to AppleCare are falling on deaf ears. A Facebook group is now tracking the problem, offering advice and performance test suggestions.