Apple has updated Logic to version 9.1.8.

General:

• Additional content downloads now behave correctly when installing on OS X Lion and OS X Mountain Lion.
• Resolves an issue in which the Save As command sometimes resulted in an alert dialog in Logic 9.1.7.

Audio:

• Fixes an issue that caused an Airplay dialog to repeatedly appear.
• Relaunching the audio driver now reliably applies changes made to the buffer size.

Performance and Stability:

• Resolves performance issues when using plug-ins that provide frequent graphic feedback.
• Resolves an issue that could cause an abnormally large monitoring delay after a computer wakes from sleep.

Plug-ins and Instruments:

• Fixes an issue with ES2 that could create distortion when a sidechain was used as the modulation source.
• Tuner now responds consistently when used in a channel strip that also contains plug-ins which introduce latency.
• The MIDI channel for a multi output software instrument is no longer changed when adding Aux outputs when there are regions on the track.

Compatibility:

• Logic now properly maintains Aux assignments for multi-output instances of Kontakt that are migrated from earlier versions to Kontakt 5.
• Resolves an issue in which deleting tracks took longer than expected if Melodyne Editor was inserted on a track.