Initializing V-Ray Scene over and over again

I created a series of interior scenes, which worked fine in the beginning. When I reopen them, meanwhile I can read on the bottom line ”Initializing V-Ray Scene“, which can last 50 or more seconds. After each click or other action it starts again, so I’m not able to work properly anymore.
I’m pressed for time and this is very annoying.
Can you please help me to solve this problem?

Crash #387011
This is the error code, when I shut down Sketchup because of this issue.

Might want to contact Chaos Group’s customer support about this.

Thanks, I’ll do this, if it’s an unknown problem here.
Meanwhile I avoid opening the main project (which contains the big model) and work with the single apartment models instead. Somehow especially the main file (model based on imported CAD files) seems to be buggy.