Tiles pre-built or generated?

I think I read somewhere that you can run object generation code in the editor to then have objects baked into a scene. If I'm wrong about that than this question is irrelevant. However...

If I have a thousand or so "tiles" (just planes) that I want to stack together would it be better for me to generate them once in the designer and then simply assign the dynamics to them on the scene's loading (textures, sound emitters, etc...)? Would I gain performance doing this, or would it really even matter in the end?

Also, if I am generating them on the fly, I tend to want to keep them as few as possible because of the generation time, but if they were baked into the scene could I get more of the actual objects out there, or is the object count what's really killing me in the end?

Thanks much in advance for any and all advice.

not really sure what you mean by tiles... but if you mean terrain then just make one by going to the top menu bar and click terrian,and create terrain. but if your asking about putting different objects in a scene using one prefab then you can create a new prefab and drag all the gameobjects into that prefab. but if your asking if too many objects in a scene slows down unity then no matter how you group them... unity wont slow down very easily.

sorry, i dont really know what your asking.

Okay, so I ended up pre-baking the tiles from planes created by http://www.unifycommunity.com/wiki/index.php?title=CreatePlane.

I can safely generate and level-load 16x16 with minimal impact, but going too far over that generates too much strain upon the initial rendering. I'm guessing it's because they are more than just planes (they are fully instantiated GameObjects), but either way - it's working now.