This update addresses overall stability and performance issues including:
Fixes an issue that caused an AirPlay dialog to repeatedly appear.
Resolves performance issues when using plug-ins that provide frequent graphic feedback.
Additional content downloads now behave correctly when installing on Lion and Mountain Lion.
This update is recommended for all users of Logic Pro 9.
For detailed information on this update, please visit this website: http://support.apple.com/kb/TS2565