VERY ugly bug: Sluggish GUI with enabled Tempotrack

So, I made a little video. You can watch it directly via Dropbox by clicking the link. Please watch carefully and then do not tell me that this is a workflow issue. I am going mad here because of this bug, Nuendo is almost unusable, I am in Cubase mainly these days, but Cubase slows down as well when you start slice-editing. Here the whole thing becomes sluggish after a while, when dealing with longer songs espessialy.

Sorry for the bad english, just watch the cursor line following the scissoir tool - usually I am using alt+click usually but I had to hold the iPhone so I had to use the scissoirs for demonstrating, it is even slower when holding down alt while moving the mouse: