Bug AND optimisation issue: I'm reaching 800 instrument channels in the template. All are disabled and hidden with the group function until I use them, so it's not related to amount of loaded tracks or memory usage. This is now days industry standard way of working with film scores for most composers (although there are some exceptions).
This causes two problems in Logic:
1. At high track counts, even if everything is unloaded, the GUI and the software overall becomes sluggish, laggy and unreponsive. The simplest tasks can (randomly) freeze for 0.5-1 seconds. Like splitting a midi event. Or switching windows, or track. Or Undoing. Again, even if it's visually hidden in both Arrange and Mixer.
2. The worst thing with this is that Logic seem to have a bug in the Keyboard input buffer. This means that it doesn't cue up keyboard commands during these freezes, instead ignoring them. An example would be copying an event in the Arrange Windows. Moving the event, then pressing [Opt] for duplicate, if the lag occurs in the middle of this sequence (which it often does), the event is moved instead, ignoring the [Opt] command. Then undoing freezes, and you have to re-do the sequence, where it lags again. Etc. So it's simply not a viable workflow option.
I've tried various solutions: Disabling Auto-backup, reduced number of Undo-steps, pruge:ing the Undo history. Nothing helps. This occurs both on my Macbook pro 16", 64GB RAM machine, and my iMac Pro 128GB RAM machine, and if a DAW requires higher VISUAL requirements to display stuff than this, it's simply just badly built. I don't know when this started, but I used a very large template a couple of years back (for a while doing empty templates as an experiment) with no problems, so it has to be something in a later version this started.
The template it built in 10.4.8, and had the same problem there. I don't have time spending a full month trying to rebuild the template again in 10.6.1 just to see if it works. If no one here finds a solution, it should be considered a bug.