I recently did do something very very similar whilst creating a game. I had massive problems with benching a papervision game I was making:
On a flash forum I said this...
http://built4flash.stackexchange.com/questions/197/effeciency-of-material-swapping-in-papervision
The Game itself renderers roughly 200 cubes as separate planes. 4 visible planes with texture.
When I first preloaded this custom cube into memory - traversing them all would take about 45 seconds to a minute.
In this instance I do swapping of materials to achieve my result. In essence, rendering the same corridor game in colorMaterial's takes 2 seconds. (then I swap materials later for real texture whilst running around)
Currently the game runs on my laptop at roughly 8~15 frames a seconds (bad I know but its old for testing) same thing for color materials I easily fun at 40 frames and no render problems.
You can see the final game and judge for yourself.
(Press roboidz run link at bottom of the game to see it.)
http://tinyurl.com/y2fg44l
If you need a cut down version of this part of the code I'm happy to help.