I have converted buildings that include much meshes into blueprint (few 100s meshes). After that its much slower to change settings for the meshes (if compared to grouping which work near instant). With i7 5820K, I am getting ~5-10min freezes in editor when changing e.g. cull distance setting or mobility. Also if editing component location in blueprint, the movement is very slow.
Edit: Got one crash when trying to change mobility in editor view → blueprint details - MachineId:F87B756443F95CE9986941A672FE5264