I've had this problem since Friday. I have Comcast too, and I'm in Chicago, and as soon as it leaves the city and hits the Level3 point (hop 4) I get "request timed out". Lost packets all over, 2 second delays. It made even chocobo racing a rubber-banding nightmare.

Tonight I had the same issues, so I installed VyprVPN on a recommendation for alternatives to WTFast. I first tried NY's server but while I got better packet reception the ping was not much better. Picking the Canada server (in Toronto) and my experience smoothed out substantially. I'm going to have to see how it looks after maintenance, but unless S-E harasses Level3 for whatever is causing this traffic jam, I doubt anything will improve.

EDIT: also to anyone who wants to tracert to Excalibur the IP I used as a reference point is 199.91.189.35