Playing on Cactuar and suddenly had a huge lag spike.
DC'd about 5 minutes after it started. Tried to get back in, was put in a queue, and then DC'd almost immediately after getting back in.

I think this may be just for players in the US, because one of the party members said they were playing from Canada and were fine. My friend I entered the dungeon with is playing from the UK and isn't having any lag.