Strange ability lag?

[Vahlnir]

Combine that with the fact that XIV has been under massive DDOS/server lag the past week or two, and that's very likely the cause of the issues you're dealing with right now, for the casting as well.

This is exactly what I've had to deal with lately and is certainly the root of the problem for me. Even when they say the game has "recovered" at night the problem still persists, though definitely slightly less than it does during the day. However, once the attacks cease entirely as they did last week I was able to play with 0 lag and 0 ability delay. So yeah, I think it's safe to say that this is the main problem.