I noticed the lag with pressing the super key in unity, as well. Then I found out that Super+a is apps, Super+m is music, etc and that anyone of those is usually faster in coming up than a pure Super (for the default lens or whatever). I'm wondering if it's "waiting" just a bit for that +[a,m,etc]...
That can't be it. That would only require waiting until you release the Super key. Instead Unity waits about half a second after releasing the super key before the dash appears.
