Non Transparent Sprites

Are there any options for rendering unity sprites non transparent, and/or non-tinted for ultimate speed of rendering..... pretty much just a blit with scale ?

I can make my own shader to do this..... but wondered if Unity can do it also, as I cant find options to do it.
2 questions...

1) if a sprite has no alpha channel.... does unity know it, and render accordingly, without transparency enabled in the shader?

2) in Unity Sprite Default material shader... is there a way to manually turn off transparency rendering (in the shader) of a sprite (regardless of alpha channel in the source texture?