Imported Scene is Very Slow – Deleted and Undoing Takes Forever After importing a model from Google Poly (via fbx), I have a scene with


8.8k tris
4.6k faces
24k vertices


There are no modifiers active, and adding / editing / navigating are working very smoothly. However, undo, joining objects and especially deleting objects is incredibly slow (5-20 minutes per action). 

I have never experienced something like this before in Blender.  How can I improve on this situation?  

Also, a side note: why are the edges purple in edit mode?
The .fbx file does seem rather resource hungry for such a simple scene. I've downloaded the .obj version for comparsion. Counterintuitively the .obj is both smaller in file size and loads much quicker despite being a ASCII text format. The reason seems to be that in the fbx import all objects are parented to empties and every object has 25 materials assigned. This increases the scene complexity and dependency graph that has to be constructed on import. The actual geometric complexity is identical, none the less the effect is quite profound since the fbx import requires 542.9 MB of memory compared to the 44.5 MB of the .obj import. The solution would be to use the .obj instead of the .fbx file.


Scene statistics .fbx


Scene statistics .obj

The light blue edges are marked as sharp.