first off you need to get a memory stick but you need to keep your hard drive in configure your usb, launch halo 4 use that usb to save the game on don’t worry you game data will be on your xbox live profile E.G what levels you have completed now go to the campaign, when slows down when loading go into skulls and just keep turning the iron skull on and off as this will slow down the percentage bar whilst still loading the game therefore making it 100% loaded.
hope this helps this might not be a permanent fix but it will work for now whilst 343 I fix the issues with certain consoles.
I found this out myself as I kept clicking the skulls and it slowed down the loading speed but loaded more data.