detecting player

Hi, Im trying to use Physic2D.Linecast to detect player and I was just wondering if I were to attach this to my game background, would this help with performance

Code (CSharp):

1. playerIsHere = Physics2D.Linecast(alertStart.position, alertEnd.position, 1 <<LayerMask.NameToLayer("ThePlayer"));
2.         if(playerIsHere){
3.             renderer.enabled = true;
4.             Invoke("KillBackground", 6f);
5.         }