I am not a technical person, and I'm not sure what I am about to suggest isn't a possibility. All I can say is that I have had enough experince with Mac's to know that a new vanllla Mac from Apple with and OS version "ready to install" i.e., with no hardware conncted, is different than the same Mac after the OS is unpacked, after recognizing hardware, of as manof us do checking the boxes to copy settings etc., from a previous system. The OS by design sees hardware that is connected, and copies other settings, like prefences - some of which are placed in the App Support flders, or one of the two other Libraries (main system and user).
This means that there is likely to be one or more files, settings, system preferences that affect performance in way we cannot imagine- and Logic may be an unfortunate victim. Even setting that relate to Apple pro apps like Final Cut Pro X may have dislay preferences that could under certain conditions affect something about the way Logic sees or reacts to (for one example) a control surface, including "a sapce bar," or the display, or the transport, which is a software controller of sorts.
I purchased a seemingly clever and simple device from Novation, called an SL (something). It required me to install the latest software interface for it to work. All I really wanted was its transport control, howver the installer changed hundreds of unknownn "things" in my system. Ths was when the Lag probem started for me- and t was much more dramatic than now. I spent hours on calls and with emails back and forth to Focurite tech support. In the end I uninstalled the software and returned the device, deleted Logic prefs and CSU file. I have no control surface now but I do have the Lag.
Logic, for some reason, was not designed to be independent of Core Audio (either) in the way that other DAWs are. It assumes a Mac is used for obvious resasons. As a result, it is more difficult, impossible, to reassign track routings, audio regions, and other Audio settings in the way an app like Cubase does (using VST). I am not suggesting Cubase is a better DAW, or VST is a superior technlogy or wrapper or whatever, and it has had its own issues over the years. What I'm saying is - agreeing with these other posts - Apple has to be looking at the OS, the otherwise tangled yet ought-to-be unrealted bits of settings, system and app support files, that cause these type of anaomolies and behaviors.
When 10.8.2 was released, a Final Cut Pro X update came out simultaneously. I produce some TV and was using the new app, which was being trashed at the time. Out of nowhere, in FC any video in my timeline became posterized. After three days of phone support, all the way up to CPU senior level where a guy had me set up a new users, begin trashing all my user caches, prefs and app support files and folders, my phone's battery went dead. I decided to bail out. I called Apple the next day and got on with a GENIUS named David, who put my on hold for ten minutes, and came back saying he found "something" internally documented and had one question - "Do [I] calibrate my Cinema display?" Yes I did. He asked me to change it to "Default." Problem gone! Out of the box thiking. Apple!
I installed a Canon scanner once on an old laptp. I got stupid error messages every time I installed an app on my 8-Core that I copied personal settings from. (i found the single cause an deleted it) We install apps and unistall them. "Errors" we find in Disk Utlility coming from "nowhere," but are supoosedly begnine.
My point it that thee are certainly thousands of connections among the OS, apps and software we do not know of. Third party apps that were tested by Apple and plug-in companies. Any one of dozens of these could be the cause for this Lag. These could have been put there by an old piece of hadrware, an app or the OS - recognizing any of these - and these can be connected to display, USB (keyboard), Core Audio, memory conflicts. plug-ins, yada yada. Remind anyone of Windows over the years?
Anyhow, that's my two cents. I want to recognize and thank all of you for particiapating and helping the team at Apple. I too love Logic. I use a few DAWs, and have had to reply on one recently. There are other issues with Logic that have been much more troubling for me (I meantion one above). I look forward to a fix (Logic, OS or both- and the new version). I see myself using Logic for a lot of my radio and TV audio production. I'd like to recommend a DAW that I have also used over the years but is now amazing. I will not do this here because it unrealted to the substance and reason for my post (buried and unkbown connections in the OS and Logic's behavior). And I don't want to jeopardize my (long winded) comment being trashed. We're all interested in Logic...
