There appears to be a time limit on how long I can use Dimensions for on large projects as it will crash, but not close. I have no ability to force quit the program either and am left with a black box on my screen. I finally have to force restart my Mac as the machine will not restart as long as Dimensions is open (and as mentioned I can't quit it). I haven't even tried to render a large project yet, since I can't work for more than 10 minutes without the program crashing. The program does give me a 'warning' before it crashes -- It starts responding more and more slowly and becomes laggy (but the rest of my computer responds just fine).
I am using iOS 11.1
The file I am working with is an obj. file, that I then resaved as a dimensions file. The original file is 187.2 MB. The corresponding dimensions file is 97.9 MB.