For the people who are struggle with the GCD. Try something and see if it helps. I noticed that I had serious issues playing with it until I did this experiment.

Every time the global cool down flashes watch to see if you change direction while moving or stop entirely.
Collapse the skills and see if this will improve your game play. It did improve it greatly for me.

If you are a visual person your issue may not be the GCD, it is simply how loud the GCD indication is and it makes you focus entirely on it for a few moments, just enough for you to get in trouble while fighting.

I believe that a transparency setting on the cool down animation could solve it entirely. When I had my skill collapse I could easily do my combos and the game play was not noticeably affected either. The problem resides in the skill interface not the cool down time!

Try it!