Open/close door, lags if I walk into it.

If I make a door open and close, with this script. It opens and close fine, but if I walk into the door, it will lag insanely, until I get away from the door. When away from the door, everything is fine.

Any ideas?

 var IsOpen : boolean = false;
  
 var CanOpen : boolean = false;
  
 var Volume : float = 0.5;
  
 function Start () {
 audio.volume = Volume;
 }
  
 function Update () {
  
 if(Input.GetKeyUp(KeyCode.E) && !IsOpen && CanOpen)
  
 {
         Opening();
         IsOpen = true;
         audio.Play();
 }
  
 else if(Input.GetKeyUp(KeyCode.E) && IsOpen && CanOpen)
  
 {
         Closing();
         IsOpen = false;
 }
  
  
 }
  
 function Opening()
 {
 for (var i = 0; i < 100; i++)
 {
     transform.Rotate(0,0.9,0);
    
     yield WaitForSeconds(0.01);
         }
 }
  
 function Closing()
 {
 for (var i = 0; i < 100; i++)
 {
     transform.Rotate(0,-0.9,0);
    
     yield WaitForSeconds(0.01);
         }
 }
  
 function OnTriggerEnter (other : Collider)
 {
         if(other.gameObject.tag == "Player")
         {
                 CanOpen = true;
         }
 }
  
 function OnTriggerExit (other : Collider)
 {
         if(other.gameObject.tag == "Player")
         {
                 CanOpen = false;
         }
 }
  
  
 @script RequireComponent(AudioSource)