A friend of mine with the level meter lag I posted here
reported, that the update did not fix anything.
Your friend's Mac mini (late 2012) uses an integrated Graphics Processing Unit (GPU): the Intel HD Graphics 4000. Integrated GPUs use system memory for video processing, and their overall performance is affected by the amount of installed RAM: increasing RAM can improve performance. With 8 GB of installed RAM the Intel HD Graphics 4000 GPU allocates 512 MB of system memory to video processing. At 16 GB of installed RAM, the allocation is 768 MB. Integrated GPUs typically don't offer the same level of performance as discrete GPUs.
With the release of Mac OS X 10.8.3 [combined with Logic Pro 9.1.8], Mountain Lion is no longer a gating factor in Logic Pro's performance.
There are still many other factors affecting Logic Pro's performance:
• Processor speed and number of cores
• Installed RAM
• Graphics Processing Unit (GPU) type, speed and memory
• Display type and resolution
• Storage device type and transfer rate
• Audio interface type and transfer rate
• 3rd party hardware
• 3rd party system-level software ("Extensions")
• 3rd party audio plug-in performance / compatibility
• Logic Pro configuration:
- 32-bit | 64-bit
- I/O Buffer Size
- Process Buffer Range
• Project configuration:
- number of tracks
- project length
- sample rate
- number and type of software instruments
- number and type of plug-ins
• Data corruption:
- damaged preference files
- damaged project files
All of these factors should be considered when troubleshooting a performance issue.