Help!

Hay IStonia,
I make high poly bust of alien mech, now I made only head and it has 850 000 polys.
Viewport begin to work slow there is pause everytime I want to zoom or move or rotate. I have tourn edge on unselected - off and hide edges when rotate - ON and it still work bad. Only one thing help me is to isolate object when object is isolated and all other objects are hidden everything working good.
I have also to make neck and shoulder, and I'm afraid there is no way to finish model in Nvil.
But it is just bust, I affraid to think if I have to model all mech. Please make somethink, I LOVE Nvil... I spend a lot of time to tune it and now looks like I have to go to another software becouse Nvil do not allow to work with high poly models.

850k  is demanding for any 3d application!!  Modelling in Maya would also be really slow.

Nvil performs better with more objects insstead of 1 object that is really hi poly.

Best is to work 2x divisions lower then final render resolution.

Mason, I loaded this model in Cinema 4D and SoftImage works great in both, without any trouble... Even in Silo it works very good... Also in Nvil I used instances insted of simple symmetry to reduce PC load and no luck. But in those softwares where no any instances and it works great.
I think information about 850K is very outdated.

Andrei, make sure you have "Cull Backfacing" and "Back Face in Gray" DISABLED. Those two settings, if enabled, can bring a scene containing high-poly objects to a crawl.

I wonder why does your model contain so much polygons. 850k for a head part of a robot seems way over the top, unless it's a very, very complex mixture of hard surface and organic subdiv modelling (in which case you'd probably get better and faster results sculpting in 3D-Coat, Mudbox or ZBrush and retopologising your mesh afterwards).
Is 850k the result of an n-level subdivision or is it the poly count of your low-poly geo?
Or maybe you're not modelling with subdivs?
Just curious.

RubberDuck, "Cull Backfacing" and "Back Face in Gray" are disabled.

It is very complex and high detailed model that is why so many polligons.
I model it only with Sub-D. In sculpting software it is very hard to make this kind of surfaces becouse they are mostly hard surfaces.