I had this issue on my iPhone 4S too.
It's Comcast's log-in server that's the problem. It takes longer to log-in for some reason and everyone's phone apps are timing out after 5 seconds without a response.
Even trying to log-in on a high-end PC takes longer for Comcast than any other Email site. Comcast needs to spend some money on their webmail servers. I mean, they raise our rates every 6 months for no reason other than greed - now might be a good time to upgrade the system for your customers, hmmmm Comcast?