I'm glad to see I'm not the only person having this problem. For a while now I've honestly just thought it was a problem with my computer. Such a massive pain though as you said Wobbler with the way the lag is, it makes running things like CT and Coil just impossible. At the moment I'm getting around it with Battleping like FirstAidCat mentioned, but it's not the best of fixes as I'm using the trial version so I get 90K error'd out of the game every 20 minutes.
It's a real shame the way Square-Enix seem to just ignore their customers, I must have sent about 7/8 bug reports since I started playing this game and I've only ever gotten a reply about one of those and it never got fixed none the less. Yet someone on their staff found the time to delete and warn me about a forum post I did defending Square from a torrent of people getting annoyed about maintenance downtimes. So they have the time to tell me off for posting on a forum but they don't have the time to fix major lag issues within their game? Really makes me wonder if the Customer Service offices at Square-Enix even have any employees.