Hmm, I have over 30 GB left on C: and still get the freezes. By the way, I’ve noticed that the editor tends to freeze pretty hard if we e.g. minimize it, go browsing web for ~5 min and then go back to editor. In my case it sometimes takes a 10-20 seconds to un-freeze and get back to usable state. This wasn’t happening in e.g. 4.11, as I remember.
PS. Just freezed for ~15s. after just selecting Spline component in blueprint.