Why does single player arcade games require stable internet connetion?

Does anyone know what data is being transfered when playing singleplayer arcade?
I have a poor internet connection where i live, so i mostly play alone, but if my connection becomes unstable while playing i can drop from 150 fps to 1fps. It is possible to get around this by playing offline, but this makes discovering new maps unnecessarily difficult. Could not find anyone else complaning about this, but i doubt i’m the only one annoyed by it.
Also, is there an easier way to start offline mode than disconnecting the internet before i start the game?