Americo says in his useful http://www.dmu.com/maxatmo/
"NOT TOO MUCH POLYGONS!" when VP objects are used into Atmo worlds.
Well, this is true but I think it isn't exaustive.
My experience is this: my world is a few "jerkily" (I hope this word is correct). I would like a more fluent movement.
This world is made by only one VP object and represents a complex floor of a building.
The original file is a MAX one of about 140,000 polygons.
I have optimized meshes and textures (6) both via MAX and VP Stream Tuning, so now are only 27,000 and textures are OK.
But the movement is not so fluent.
Are the polygons still too much?
I don't Know, so I tried a test: in a simple Atmo world I put a VP textured sphere made with 27,000 polygons.
THE MOVEMENT IS FINE !!!
Not only this: if I add other four primitives, everyone with its tex and 27,000 poly, movement is still fine !!!
So I think it isn't only a problem of polygons but, maybe, also how many meshes are into VP object and how they are placed in the world.
Well, can someone explain this mystery?
May I hope in a fluid movement?
Did exist reliable parameters that allow a good control?

No-one seems to be able to answer this question

I try to keep any object under 4,000 polys, and I aim for 2,500 polys for terrain. A lot of compromise is needed, and fiddling about with textures, to compensate for the lack of detail.

Also it's helpful to place Atmo primitives in your line of sight all the time, so that most of the Viewpoint Objects are obscured, and you can see just one VPO at a time.

But seems like VPOs completely out of sight behind Atmo primitives will still effect movement, if th VPOs have a lot of polys.

It's worth doing test-worlds and placing Atmo primitives so they block your view of the VPOs, then testing movement.

I think the answer is lopoly, lopoly, lopoly

Thanks,Runner, but I don't undestand why my test with sphere etc. (100,000 polys) go fine.
So I tried whith a big hollow sphere with inside a number of high polys primitives.
Only if they are well intersected the movement isn't so good.
So I can say one sure event: if I look to my object (building or sphere) far away from it the move is fine, if I am inside it isn't so.I posted this problem also in Adobe-Atmo forum with the following results:

-Erik says: "All I know is VET goes crazy with intersecting geometry (and I suspect meshes too close together)."
-Jim Coe says: " believe there is a rendering speed issue with how many faces are visible to the camera from a particular point-of-view?"

What do you think about?

Unfortunately I can't place Atmo primitives 'cause I must see VPO and I can't use lopoly, lopoly, lopoly , without destroying original meshes.

But I can try the last attempt: I'll subdivide the original one VPO in more single meshes and I'll see the result (but I think it is a mad work for aligning all the meshes).

Other opinions?

VP objects in any atmo world makes movement choppy. I wish vp would fix this (working with Atmosphere) so that ppl can have vp objects in their worlds, and still have fluid movement. There is no reason why this can't be fixed. I just don't know what the fix is.