Will really just depend on (1) the lines at security and (2) waiting time for the transfer bus. But I don't think the difference is meaningful on average. There should be pre-check at concourse C.
I would probably use the Centurion lounge and have real breakfast, although frankly, for an 8:25am flight I wouldn't be planning to get to the airport with much lounge time, I'd rather be doing other things, like sleep.
