Can. you give the exact configuration of your setup including disks and how you have organise your disk(s).
(where is the system, the libs....)
Include audio parameter in Logic and in Ve-pro
Also can you give what is running on your master and on your slave
As you use many libraries you must test them to see how greedy they are
One trick in Logic to better use the different processor is to use VIs instead of VE-PRO
If you use SSD or Raid 0 of SSD you can reduce the preload buffer size.
Another is to have VSL on VE-pro and other libs in Logic that you root to MIR via an audio track
At last can you give memory and disk meter in Activity monitor when you get hick ups
I had very bad surprise on a Choir libs eating all the memory !
I have very bad souvenir when I was using QLSO, it was so greedy, this is why I move to VSL
Another trick is to use Dry instruments and to add reverb on busses !
As I told you before if you are in trouble with too many track you convert the most heavy track to Audio track as an audio track use less CPU
5.1 o 7.1 recording are also much more greedy
The best trick on a computer is to spread the tasks and avoid to add layer to a task
VSL has work very hard to optimise the VI libs, this is not the case of other manufacturer of libs
You can write quatuor with instruments using "a lot of note at high tempo" and let it play by you different libs and see what is the library that is the most greedy !
You must also be careful if you have big tutti
Writing orchestral music on a computer demands either a lot of money to have a big setup with one master and many slaves or to be able to monitor what is happening the you run into clicks, pops ...