For the people saying that it's all ping and there's not much Squeenix can do about latency, that's only true in the most technical, trivial sense. Yeah, we're limited by distance, the speed of electrons in a wire, and bottlenecks as packets jump between nodes. That aside, many modern games with an online component have developed tricks for masking that latency which XIV could use, but frequently doesn't.

The way the client handles the reply to a request to use an oGCD and the {redacted non-TOS respecting things} that have been developed just to make FFXIV behave like an MMO aware that its clients aren't on Japan's giant LAN does. The cause behind and the fix for that specific issue is well-documented. Square hasn't implemented it.