Would this cause slowdown...

Hi. In order to better organize my project files I am not using materials very often. Rather I just attatch this script to most of the objects in my game. When I run my game on an iPhone 4 I am running into some slowdown issues…could this be one of the things causing it?

var Art    :    Texture;

function Start   (){
    renderer.material.shader =  Shader.Find( "Transparent/Diffuse");
    renderer.material.SetTextureScale = ("_MainTex", Vector2(1,1));
    renderer.material.mainTexture =  Art;
}

The main problem with your “solution” is that all objects will have a dedicated material. No resource will be shared. As a direct consequence the draw call rate will be very high.

Is is really a bad practice to make materials on the fly. I strongly suggest that you make materials in the editor so that object can share those materials and reduce the number of draw call.