I have tested GM1 on both a new Macbook Air and new Mac Pro and the UI is extremely jerky compared to Mavericks, particularly when it comes to window resizing. Resizing in column view with several columns up can get so jerky that I'm getting flashbacks of 10.0. I also notice that opening a large fan from the dock is not smooth anymore and even something as simple as dragging windows around seems to have the stutters. Again, this is on two separate systems which both have current & perfectly competent hardware. Does anyone else notice this?