I cannot believe I have only just thought of this.
It's so simple. DOH!
Open a second separate instance of ACA.!!
I don't know about you but I often have more than one project to work on or maybe you have the one project but more than one drawing file to work on.
Do you sit and wait for the computer to catch up, for regeneration to finish, sheet sets to open or worse when the drawing locks up and you know you will be waiting minutes for it to resolve where you can continue working. Sometimes it might be a bug (feature!) that locks up.
Often I am working on a base drawing and then a second drawing where the base is referenced in. If they are both opened with the same instance of ACA, then if one drawing is busy, you cannot swap to the other drawing and work while you wait. Coffee time.
HOWEVER, if you are smarter than me, you have opened a second instance of ACA and then opened the second drawing which means it's a completely different thread and you can jump over and work on the other file until the first instance has resolved.
I've had 4 open at once this week. Options!
On a reasonably fast computer (mine is from 2011) it's not that hard.