Although the 0.3s number is constantly referenced, the lag is considerably more than just 0.3s. An easy way to see how bad this game lags is just start autorunning and try to cast a spell and see how long before your client realizes you're not supposed to be able to do this. You can even have your client claim you finish a 1s casting spell (say, mount chocobo) while running continously. In an ability lke WotL, the lag double dips, as you're getting a delayed notification that the ability is being cast (very easy to see this if you have a running start), and of course when you're attempting to dodge it, you're also subject to the same lag again.
