Apple has released Mac Pro Audio 1.0 (http://support.apple.com/kb/DL1004). This update is for Mac Pro (Early 2009) computers running Mac OS X 10.6.2.
According to Apple, this update reduces processor utilization during audio activities, such as playing or recording music. audio activities, such as playing or recording music. It’s a 1.64MB download.
You can obtain Mac Pro Audio 1.0 via the Software Updates component of the Mac OS X System Preferences app.