I play on PS4 and don't have any issues normally...nothing like what you are experiencing. I have had some lag spikes this morning and afternoon running FATES in N.Thanalan but that is to be expected with how many are running FATES there leveling. Overall though my game runs smooth.
The main issue I have in in PvP "Seal Rock" that one I have had some really bad lagging and disconnecting issues, not sure what going on there.