I’m in Canada on 1 Gbps fiber optic, and did a new install of MSFS on Xbox this week.
The main installer Base Game, and World Offline Mode, together are +120 GB, they downloaded for me at about 500 Mbps, less than an hour.
But the World updates, downloaded inside MSFS Content Manager, average download at about 10 Mbps and it takes me about 2 days (I only download 1 at a time because if I don’t, thereis always an error of ‘xxx file failed to install’.)
I think it’s apparent that the main game file is on a fast server, while the World Updates are not.