As the title suggests. It is pain in the ass if you are working with alot of subtools. Everytime you import a new mesh, it iterates through every each of them(Says "Switching to subtool ‘Name’ "). If you have a say 20-30 subtools it can take up to 15 seconds. Kinda breaks your workflow for a moment.
I am importing from Maya 2018 to Zbrush 4R8.