I have the same issue as you, OP. I've been playing this since beta/early launch with no latency issues until today. And all day I have been plagued with lag spikes making this unplayable. I have also tried logging on NA/JP servers with the same issue (I play EU). I'm also very positive it isn't my net after doing a check on everything. FF14 is the only game I am having issues with today. I hope maintenance on Wednesday fixes this.