The just released new stable version 2.1 on November 1st .. all of the speed lagginess has been fixed, especially with the mouse, and as well rendering issues I had with Mountain Lion on some window graphics being all distorted or squished for applications like Messages are all fixed too! WOOHOO!
I have not tried multiple menubar option, since i turned that off and didn't like it anyhow, but I hope that is fixed too!