This may be an issue with SE, but it may also not be. I have a very strong feeling that it's a combination of a few factors.

The game has hit a pretty huge amount of subscribers and simultaneous connections to their servers which must be routed through internet backbone servers in and around the NA datacenter area. Many of us have been researching this, and have found that the lag is caused due to high ping, packet loss, and/or timeouts while routing data through these servers (not ffxiv servers btw - Cogent, TATA etc.. are known offenders).

A couple things happened to start off this lag with me, namely the first big maintenance that opened up the servers to more players, and the subsequent massive increase of players using each ffxiv server simultaneously. From what I've been able to gather, it seems like SE changed the shaping of either the type of data they send, or amount, and it's simply overloading the backbone servers used to connect us to SE's servers.

Naturally they will not be saying much or anything about the problem to us as:
A: It's only affecting a non majority portion of players
B: They likely don't have a solution yet

I've come to the conclusion that we will simply have to wait this out, and hope that SE manages to get the issues figured out in a reasonable time frame. Which sucks, because if it's not fixed by the time my free time is over, I'll likely not continue to play until it is fixed. And that is unfortunate, because I love playing this game when it works.