Not sure if something is changed here but I have a feeling the screen edge scrolling in beta4 is a little bit laggy, I mean the camera doesn't move instantly when I move the mouse to the edge. Not sure if this is the same as previous betas, but it feels pretty obvious to me now.

yes, i think it's related to some camera changes they also made with the "smart camera." there's a bit of an "easing in" of the screen scrolling. it took a bit of adjustment (and i had to disable smart camera), but i don't even notice it anymore.