Notepad++ has the best feature ever: Autosave without a filename. Just close and open and everything is the way you've left it.
Eventually I figured out it only reloaded the file if you can few enough tabs open so I could just open a bunch of other files, let it crash, open some more and then eventually it wouldn't load the huge file, so I could close the tab. But still, such a pain.
It was many years ago and I was young and stupid, so there's probably a much better way. But I've moved on to Linux and to Emacs now