Yeah. lots of people have noticed this.

Couple things. First of all, regardless of any other issues you may or may not have with latency etc., you need to be out of the red before the cast bar finishes. Not before the red disappears, not before the ability animation happens. Basically, you really can't afford to wait at all. See red, get out now.

Second, something that's been suggested to help is to turn off floating text and to not limit your FPS. There isn't a ton of anecdotal evidence about them either way, but those settings do seem to have helped some people.