FBX import stuck at 100%

I want to import a 90MB large .fbx file into the contents of my project and drag them from there into the level. The import dialog says, there are a total of 793 files to be imported.

The import process bar has reached the 100% an hour ago and says “Importing (793 of 793)”. This is very annoying, as a 90MB file should not take this long to import, or should it?

My activity monitor shows activity on all cores of my machine.

Can you tell me, if I should wait or stop the program? Also are there certain things with the .fbx, I have to pay attention to?

Edit:

Now, it finished importing, but the UE4 Editor window is inactive and I got this warning log:

No smoothing group information was found in this FBX scene.  Please make sure to enable the 'Export Smoothing Groups' option in the FBX Exporter plug-in before exporting the file.  Even for tools that don't support smoothing groups, the FBX Exporter will generate appropriate smoothing data at export-time so that correct vertex normals can be inferred while importing. 
Hindenburg_Ringler_Modelliert_TriSet_035 has some nearly zero tangents which can create some issues. (Tolerance of 1E-4) 
Hindenburg_Ringler_Modelliert_TriSet_035 has some nearly zero bi-normals which can create some issues. (Tolerance of 1E-4) 
Hindenburg_Ringler_Modelliert_TriSet_037 has some nearly zero tangents which can create some issues. (Tolerance of 1E-4) 
Hindenburg_Ringler_Modelliert_TriSet_037 has some nearly zero bi-normals which can create some issues. (Tolerance of 1E-4) 
Hindenburg_Ringler_Modelliert_TriSet_172 has some nearly zero tangents which can create some issues. (Tolerance of 1E-4) 
Hindenburg_Ringler_Modelliert_TriSet_172 has some nearly zero bi-normals which can create some issues. (Tolerance of 1E-4) 
Hindenburg_Ringler_Modelliert_TriSet_267 has some nearly zero tangents which can create some issues. (Tolerance of 1E-4) 
Hindenburg_Ringler_Modelliert_TriSet_267 has some nearly zero bi-normals which can create some issues. (Tolerance of 1E-4) 
Hindenburg_Ringler_Modelliert_TriSet_283 has some nearly zero tangents which can create some issues. (Tolerance of 1E-4) 
Hindenburg_Ringler_Modelliert_TriSet_283 has some nearly zero bi-normals which can create some issues. (Tolerance of 1E-4) 
Hindenburg_Ringler_Modelliert_TriSet_317 has some nearly zero tangents which can create some issues. (Tolerance of 1E-4) 
Hindenburg_Ringler_Modelliert_TriSet_317 has some nearly zero bi-normals which can create some issues. (Tolerance of 1E-4) 
Hindenburg_Ringler_Modelliert_polySurface19073 has some nearly zero bi-normals which can create some issues. (Tolerance of 1E-4) 
Hindenburg_Ringler_Modelliert_ZwischenHaus_002 has degenerate tangent bases which will result in incorrect shading.  MikkTSpace relies on tangent bases and may result in mesh corruption, consider disabling this option. 
Hindenburg_Ringler_Modelliert_ZwischenHaus_002 has some nearly zero bi-normals which can create some issues. (Tolerance of 1E-4) 
Hindenburg_Ringler_Modelliert_Plane_002 has degenerate tangent bases which will result in incorrect shading.  MikkTSpace relies on tangent bases and may result in mesh corruption, consider disabling this option. 
Hindenburg_Ringler_Modelliert_Plane_002 has some nearly zero bi-normals which can create some issues. (Tolerance of 1E-4) 
Hindenburg_Ringler_Modelliert_Plane_016 has some nearly zero tangents which can create some issues. (Tolerance of 1E-4) 
Hindenburg_Ringler_Modelliert_Plane_016 has some nearly zero bi-normals which can create some issues. (Tolerance of 1E-4)