Could you check if there is any difference when you have the mods turned off in a new game or list the mods you have? We have several similar reports but only from people with enabled more than 40 mods at once, so we can't be sure which of the mods is causing it.
I added in a new mod today called Argofox radio network. It's a large mod over 456 mb in size. I noticed when adding it then restarting game and going into the mod manager from the main menu it's taking just as long to do it's spinning logo checks on all the mods I have as when i downloaded argofox which took me close to half an hour.
Is the mod manager literally redownloading mods each time you start the game? For me on 5 mbps internet that's bad.
It now took about 30 mins or so to check mods now as i literally have to do this step each time of going into the mod manager before even attempting to start a new game or load a saved game. A large radio station mod shouldn't slow the mod manager down on xb1. It shouldn't be redownloading or bit checking each mod one by one.
I hope this behaviour will be patched. Maybe have it just do a very quick version check and if there is one then just have it prompt the player to download an updated version.