How is unity with tiled graphics?

So we’re looking into randomly (or perhaps mapped) tiling systems. So for example if we have a ground, and we have the tiles 1, 2, 3, 4, and 5, the output may look something like this:

1 1 1 1 1 4 1 1 1 4 1 1
2 2 3 3 2 2 2 2 2 3 2 2
5 5 5 5 5 5 5 5 5 1 5 5

No particular reason for that layout, just as an example.

The question I have is should we do this in unity, or should we compile our textures in an external program. The reason I ask is lag. If we have a game object, and give it a bunch of children, all of which are just sprite renderers with a position, will it cause extreme amount of lag to have all those little boxes? If we can get away with doing it in unity, we’d like to, but if necessary, should we generate the mapped texture in an external program, and load those into unity? Has anyone had experience with this?

I am using tiled graphics for generating environments. You will not have any lag as long as they all are from one source atlas.
I have been using like 300 tiles to generate both BG and FG and Draw calls doesn’t exceed 10. If you use multiple atlases it might go more.

something guidelines that I followed:

  1. Non Uniform scale values. Dynamic Batching doesn’t work.
  2. Tiling will only work on devices released before 2011[iOS excluding iPad2, will not work on iPhone4 or below] and 2012[Android]