i have had fallout 4 for almost 2 months now, and anytime the game would autosave or quicksave it would only take a couple of seconds, but for the last week autosave and quicksave seem to take 20-30 seconds, as well as the loading screens between areas being black/blank other than the vault loading logo in the bottom right corner.
there has also been an issue with the game returning to the xbox dashboard when i try to fast travel.