There is currently a major unexplainable delay when executing. It takes an extra half second or so after pressing the button before the move is performed by your character. It’s not caused by global cooldown or anything like that and I believe it to be a bug. It happens to other abilities like overpower and mortal strike too but seems to almost always occur during executes. Please please please check it out.
I will confirm this bug. It feels like execute has a latency of 600ms-1000ms, but other skills work at 60-70ms with no visible delay.
I am playing on classic. Coming from a vanilla server that had no such lag it is very noticeable.