I just found a solution to Logic Pro X Gui Lag.
I get awful lag in the Gui when my session starts to be heavy.
Just for the record, my Mac Pro is a power horse 12 core monster with 48 Gigs of Ram and an NVIDIA Quadro K5000 graphics card.
So. It's not the Hardware that causes my lag. It's the software - no doubt.
The more the tracks and the more regions I have in my session the more lagish it all becomes.
It's been like this for years and years with Logic.
I regularly work with more than 100 or 150 tracks with about 60 to 100 instruments.
However I never have more than 10 to 15 instruments playing together.
Sometimes I will need to wait between 2 and 3 seconds for the GUI to react to my selection operations and some automation dragging operations.
This is consistently happening on regions, notes and automation data selection, and also automation value changes.
I'm glad to report that a couple of days ago I have discovered a solution that has helped seriously diminish my lag issues. Including on a 5 hour LogicPro X session with 200 + tracks.
The answer : Close track stacks, or hide tracks as much as you can.
That's it.
Why did I not think of this before is beyond me..
It just works.
When you hide tracks or close stacks you vastly simplify the content/data that Logic needs to handle to react to your clicking and dragging
Currently when I'm under 30 tracks left (visually) after closing track stacks, on my monster session, I get a visual lag that's under 250ms.
It would probably be way more snappy if my session wasn't 5 hours long.
Please note that the lag I'm talking about here is only related to how the app reacts to mouse clicking and dragging.
It's mostly a problem that people who work with BIG sessions and a lot of tracks.
It's not 'audio metering lag" which is another subject.
I really hope this helps LogicPro Users.