Once again another question for someone coming from 12 to 15…in 12 I can close Projects and open a new one…in 15 when I try to close a Project “Unloading MixConsole” comes up from anywhere to a couple of minutes to closing Nuendo through Task manager! I never had an issue before but 15 has me stumped 
It is there, to ensure stability while a project unloads.
Nuendo 12 was stable, never crashed on me and I was allowed to close the same projects that in 15 give me time to go shopping or read War and Peace…I look at stability differently
There is actually an unloader for the project itself, and the MixConsole.
I believe there should only be one unloader, not two.
The project actually unloads fast, it’s the MixConsole that can take forever
Sometimes, the mix console unloading slow is from 3rd party plugins running stuff in the background. Arturia Software Center hangs for me ALOT. If you go into the task manger or activity monitor (depending on your OS) and end the Arturia task (might be a different plugin app), and this usually fixes the unloading mix console hang.
Unfortunately, it appears that we need 2 unloaders, one for the project, i.e., instruments and one for the MixConsole.