[vtkusers] slow interaction when i render 1000 spheres

[Dharmendra]

Hello All,

      I have posted this time and again.Though i got replies i could not 
impove the speed.

I have a question.

Iam using vtkNightly on both windows and linux.
Using Python22

My question is when i try to render some 1000 spheres it is very slow.
But MayaVi is able to visualize brain.vtk file and the interaction is 
normal.(i dont know how)

the way i do is as follows:

i create a assembly and add the actors(1000 actors one for each sphere)to it.
I add the assemble to renderer.

rendering is very slow in this case and interaction like zooming and 
panning are dead slow.

Is this the correct way to create so many actors or is there any other way.

  I need some help in this regard.

thanks
dharmendra