Editor very slow. Saving scene with no changes takes over 1 min.

My project is over 20gb, and my editor is REALLY slow long ago. Any operations with AssetDatabase take 30-40 seconds, updating prefabs takes 30+ seconds, etc.

But the most annoying part saving a scene. Sometimes its instant, but sometimes it takes over a minute (same scene, no changes in both cases). Every time I save its a lottery. Below is a screenshot from profiler after saving a scene when it took over a minute:

What is OnDemandScheduler.StopAndWait responsible for? And why is it taking so long? Anyone experienced similar editor issues?

where did you get that tree list?

as for your issue it appears is the bug that affects a lot of us where unity freezes for minutes as explained here

Thanks for the link. I used deep profiler to get the tree