Door script lag with rotation (Quaternion.slerp ?)

I'm having some trouble using this slightly modified door script (javascript) I found off of Youtube. It works fine, but the problem is that I get a huge amount of lag from it. I've isolated which lines are causing the lag, and it is the Quaternion.slerp operations, and I have no idea why.

I have experience with coding but not with javascript in particular, nor am I familiar with the transform options. Can anyone point out why this script lags? I imagine because it is grabbing information every update when it doesn't necessarily need to, and that I could write a "sleep" function that skips any transform operations after the door has completed opening or closing, but that still means I'll get a bit of heavy lag for the few seconds while the door is swinging.

Any thoughts?

Thank you very much!

 // Smothly open a door
 var smooth = 2.0;
 var DoorOpenAngle = 90.0;
 var DoorCloseAngle = 0.0;
 var open : boolean;
 var enter : boolean;
 
 var myTransform;
 
 function Awake() {
     myTransform = transform;
 }
 
 //Main function
 function Update (){
 
 if(open == true){
     var target = Quaternion.Euler (0, DoorOpenAngle, 0);
     // Dampen towards the target rotation
     myTransform.localRotation = Quaternion.Slerp(myTransform.localRotation, target, Time.deltaTime * smooth);
 }
 
 if(open == false){
     var target1 = Quaternion.Euler (0, DoorCloseAngle, 0);
     // Dampen towards the target rotation
     myTransform.localRotation = Quaternion.Slerp(myTransform.localRotation, target1, Time.deltaTime * smooth);
 }
 
 if(enter == true){
     if(Input.GetKeyDown("f")){
         open = !open;
         }
     }
 }
 
 //Activate the Main function when player is near the door
 function OnTriggerEnter (other : Collider){
 
 if (other.gameObject.tag == "Player") {
     (enter) = true;
 }
 }
 
 //Deactivate the Main function when player is go away from door
 function OnTriggerExit (other : Collider){
 
 if (other.gameObject.tag == "Player") {
     (enter) = false;
 }
 }