I have recently been through a couple of weeks with a slow and jerky internet connection, due to a faulty media box. They finally replaced it and evertything works fine, now. I have also been working the Tree and saving without problems today.
What I might add, as information, is that WikiTree was among the sites most sensitive to my bad connection. It was even slower than Flickr, with all its images. Very frustrating, many attempts to get pages to load - and yet I continued ;-)
Wishing John luck with his troubleshooting!