Welcome to the club.
Apparently this has been fixed in Cubase, but Steinberg chose to release Nuendo without the fix for these issues.
It looks like being able to zoom and navigate without sluggishness or have mouse input interpreted correctly is a music only function and thus not relevant to audio post users. (or at least that’s what some people in Hamburg seem to think!) Despite the fact that this makes the software completely unusable to those affected, Steinberg have decided to strat XMAS holidays early this year and postpone the release of the fix. Or, to be more precise - they have decided to say nothing about the matter.
Bottom line - stay with Nuendo 7 or switch to ProTools if you are affected and wait until the next iteration of N8 is released. If you are lucky and they feel like fixing N8, maybe some time next year it will turn into a usable software for you…on the other hand maybe they manage to break some other essential part of the software. What about the ability to use plugins? Or record audio? Or they could deactivate the space bar, so that you can only look at your session and not hit play, that would be great for a change.
But diabling the ability to properly use a mouse is something special, I have to admit that. Let’s give them a price for innovation. And another one for not fixing it. Real PRO software, if you ask me.