Try creating a new map, and change the engine Quality to "High". Then, exit the editor and save the map. That'll enforce that the editor settings will get saved too. Then quit the editor.
From that moment on, the Editor will load with engine settings set to 'High'. It really minimizes any crashes and freezes. You can delete the map you previously saved too, it was just a placeholder.
Thank you for providing those details. Please submit a ticket at our support site, so we can take a deeper look into this.