I'm not sure if it's because NA players live far away from the servers, but the delay in this game is pretty big. It's extremely noticeable if you run 2 characters, as they move delayed on the other character's screen.
Basically, this becomes a huge annoyance for casting spells.
If I run, then stop and immediately cast a spell, it will be "interrupted."
Why? Because the server still thinks I was moving.
My suggestion is simple, give us a small 0.5 second or so window before checking our position when casting spells. This will alleviate a lot of the issue without bringing any game breaking effects.