Custom mouse cursor is laggy on low/mid hardware

Hello,

I am making a simple game. However using a custom mouse cursor makes the cursor really laggy on low/mid computers, but it runs smooth in fullscreen on top hardware. I have read others have the same issues, and there seems to be no other solutions to it.

My question is then is there no way to solve this? Is unity aware of it?

I use for example, and all possible variations, but same results.

 function OnGUI(){
     GUI.DrawTexture (Rect(Input.mousePosition.x-cursorSizeX/2 + cursorSizeX/2, (Screen.height-Input.mousePosition.y)-cursorSizeY/2 + cursorSizeY/2, cursorSizeX, cursorSizeY),myCursor);
 }