You could just have the tiles created deeper in the hierarchy and close that folder and don't be bothered. What you can do as well is hide your game objects from the hierarchy `myTile.hideFlags = HideFlags.HideInHierarchy" not sure about how much performance would be gained.
Showing 100x100 textures on the screen is never a good idea drawing textures is more heavy then drawing polygons anyway. If you need to zoom out that far you are better off with bigger textures. Same goes for being zoomed in, you should not draw the textures that do not need to be drawn.
What I usually do (I'm not a Unity guy) is creating a Class for a map and use a 2 dimensional array for holding all your tiles. This array could be simply of ints or a Tile class with a couple of ints that refer to your textures, tile type, objects, etc. Then one would draw it as follows:
for (int y = 0; y < mapHeight; y++)
{
for(int x = 0; x < mapHeight; x++)
{
Graphics.DrawTexture(new Rect(x * tileWidth, y * tileHeight, tileWidth, tileHeigt), tileTexture);
}
}
The draw method I use seems to be for drawing a GUI but might be perfectly suitable for the task. Otherwise you have to dig into the sprite manager and find a way that works with this method.
You could use a dictionary for texture reference like int 1 in your tile class refers to some texture and int 2 refers to another. In the line you are drawing your texture you would use your dictionary to give the right texture object. This way it should not create a GameObject and thus not create all unnecessary overhead.
You can do the same for pretty much everything that does not need the level of control of a GameObject. Mind though, this way it will draw every tile of your map it most probably does not auto cull the objects like I think unity does with game objects. But just drawing what needs to be on screen is very easy. You know the screen/viewport size, camera position and the tile size. Some simple math should draw exactly what's needed.
Still, unity is a 3D engine. It just supports 2D in a 3D way. But you can basically do the same thing for quads/meshes with textures and a Orthographic camera. Just drawing those meshes needed is pretty cheap.
