Nehalem-based Mac Pro users are reporting in Apple's discussion forums and other locations that some audio tasks are causing performance issues. There is up to a 20% drop in performance while doing tasks as simple as listening to music in iTunes. Other users are saying there are similar issues when utilizing Logic and Flash.
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.