Well, unfortunately unless you have an awesome computer you will suffer lag problems. I won't deny it, but that is the cost of the detailing of the city. I may consider removing a lot of the unnecessary detailing (like muck, grass, paper and other such clutter) to reduce the sheer amount of objects in each cell, as there are currently A LOT, and making a light version which would be more playable, rather than a piece of artwork.
When we reach the stage where we are applying the finishing touches, then we'll consider adding things like the new animations. I think it's better to focus on getting the world built first.
Naturally there will be incompatibilities with mods such as NOM, LGNPC, MCA etc. but we'll look into making compatibility patches for some of them, depending on the degree of difficulty of that, of course. But, again, we'll be looking into that ONCE we've got the mod made. Gotta get that done first!