1. Sometimes after saving a script / starting playmode, editor will hang on "Completing Domain" forever, until you kill the process.
2. Not sure how to reproduce this - I have attached a dump file. My project is fairly fresh. A person on the forums has indicated this is an Unity bug, not user code related.
Here is my topic about the issue on the forum:
https://forum.unity.com/threads/unity-getting-stuck-on-completing-domain.1596090/