I have now tried to free up space on my ssd.
It seems that disk space might have been the cause for crash when loading in a level, Fort Joy for example.
But navigating some menus of resources still lock up the editor for several seconds(sometimes minutes).
For example when choosing a level to load, editing project details or when trying to publish a project.

The editor can take a lot of RAM, I have had it using about 6GB at one point, but then I still had at least 6GB unused. CPU usage almost never peaks above 30%.

It seems most text fields make the editor freeze and deleting entries that I check out from my mod package still causes crashes.

I have a friend who have not so different specs(i7 2600k, 16gb RAM, gtx 1080), the major difference is that he is using an nvidia card while I have amd.
He have no lag on any of the points I have mentioned.
Still crashes on removal of package entries.

So it might be bit of a stretch but have you always used an nvidia cards for working in the editor?