If one gets the animation 2-3 secs after the monster cast it, the latency is really bad and it will be wise not to play the event at all. It is like saying that the latency fluctuates from 300ms to 3000ms.
It might not be just the game server’s problem if that’s the case. It can be ISP problems, shared network congestion , wired or wireless connection, or software problems (excessive torrenting/software updating) that is causing the the fluctuation.