I am programming tile based strategy game, so I have orthographic view. The rendered screen has 40*20 tiles wide and each tile has got 50*50px texture. I have one layer of tiles (let's say grass) and I place walls on top of it. The game runs smoothly at 60fps now. But do I need to remove the underlaying grass tile, when I place wall over it? Because the grass is rendered before the wall and so the wall overdraws it, but I am worried about the performance cost. I render it on SpriteBatch and there is no documentation on how does the inner processes in SpriteBatch work.
So the question is: Is it highly performance unfriendly to render tiles which are not visible anyway?