I used to have this problem, but I actually found an odd fix. Hopefully it works for all of you too. What happens is if I launch FFXIV with ANY OTHER PROGRAM open, I will consistently lag for 10+ seconds at a time. HOWEVER, the fix I found is that if I close all the programs on my computer (excluding non-intensive programs such as an instant messenger) the lag will not occur. However one type of program that will cause this lag for me are all voice chat programs. Raidcall mumble teamspeak ANYTHING related to VOIP will cause my xiv to experience the 10 second lag if it is open before XIV. Try this out and see if it works for you.