About Logic Pro 9.1.8
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.
I can confirm that this update fixed the problem on my client's system that continued to have the GUI Lag issue
Also confirmed, Airplay 'bug' squashed.... and it seems that the annoying "long delay upon startup.. " that affected a few people...has now been fixed too... (At least based on the feedback I am getting from my clients..)
So far.. so good!