Ah, that would make sense then. I had double (copied) several tracks and in doing so, was copying over the effects, yet total file size was still just about 2.5 gig. But it was when I did that that I started to experience CPU issues. I went ahead last night and deleted the doubled tracks and that helped resolve the problem (along with turning off Airport).
But eventually I will need to double those tracks for more professional sounding results-but what I could do then is to "Send" the effects, and create a bus for related doubled tracks. Because I was using them as "Inserts" before. And while I don't understand the "threads distribution" concept, perhaps the "Send" effects and busses will reprioritize the efforts of the CPU in a more efficient way than the "Inserts" did.
Perhaps this would be something I should post to the Presonus forum as well, regarding CPU usage of "Sends" and "Buses" vs. "Inserts"
There is no right or wrong way of approaching a DAW necessarily, but whatever you do, eventually you hit the limits of your hardware.
By 'threads' I really meant processes. So each effect, audio channel, bus etc creates a thread or threads that your CPU executes. More cores means more threads, although some DAWs do not distribute them evenly, meaning you can get drop outs before 100% CPU usage is reached. To be fair, even very expensive DAWs like Pro Tools and Cubase suffer from this, because it's hard to get a very even distribution all of the time.
In Logic, I tend to make extensive use of freezing and bouncing - in other words, as soon as I am comfortable with a bass and snare mix and their effects, freeze those tracks and render them down as an audio file. It doesn't matter if it's not perfect because you can always unfreeze them later and tweak the mix.
One sure way of killing your CPU is multiple effects on many buses and having it all run 'live'. It'd be nice to do that, but for as long as I remember, plugins have always managed to get more complicated has hardware became more powerful.
