Gamebreaking lag! Advice?

I don't really know what's wrong. I was playing fine for a while but now I'm getting horrible lag all the time that drives me insane. Walking around I constantly see everyone synchronously walking for 2 seconds, freeze, walk for 2 seconds, freeze, etc...
When I get in dungeons or instanced battles it gets even worse! I'll lag so much that enemies are dying between periods of activity.
When I ask, no one else seems to be lagging. And I've tried resetting my router. If there's any advice people can come up with, that would be fantastic.

Note: I have Verizon FIOS in VA just like the people in this thread: http://forum.square-enix.com/ffxiv/t...n-%28R0%29-lag