I'm syncing a few saves from one xbox to another. I deleted most of my saves before starting, but it still takes ages. Can't be the data, I'm on fibre optic and downloading the actual game didn't take this long. This would be easier to accept if I knew what was happening, does anyone know?

Fallout 4 saves are pretty large and its plenty of them. Also syncking wile playing will have the game resend the quick and auto saves every times it saves.

It also depend on the speed of the server you store on.