Okay, Thursday I updated my machine to Win10 version 1903, and haven't had a freeze-hang since. I've been to three different music-club events in SL (which were pretty much guaran-dang-teed to bring a hang to BZZZZZZZZZZ!!) and got all the way through the entire event and beyond all three times. I think I can safely say the hang is history.
edit: And then, not too long after I posted the above, it hangs again. 0o This time, I'm simply looking at some text document in Google Drive, and I'm in a voice-chat conversation in one of the opensim worlds. (OpenSim is an open-source reverse-engineered workalike of SL.)