The save/load screen is so laggy, it freezes whilst it loads the picture of your save game and it's a proper 10second delay.....
It's really bad.
Do a hard reset. Holding the xbox button on the console until the console shuts off, and then after a minute or 2 restart the console so you get the green screen. This will clear your cache and should make your game better. When you first start the game, it will take a bit longer to load as it is setting up the game. Hope this helps.