Sorry to hear that you've been having issues with crashing! It does seem memory related since it occurs after importing multiple models.
If you open the application fresh, are you able to open many of those same models at once? I am wondering if it's related to importing/saving, or just the number of models in memory at once.
Also, I will be curious to see if this change to use the MultiMesh concept will make a difference at all. I except to wrap things up today and hopefully get the release out tomorrow for you to try.