Android fps problem.

The problem is that if you shoot (on a real android phone) using the gui button "shoot" the fps starting to be low. but if you stop shooting, after a second or 2 the fps is normal again. I even started a new scene to make sure there is no problem but it didn't help..

Gui script to shoot and zoom:

 var scopeCam : GameObject;

 var isInScope : boolean = false;

 

 function OnGUI(){

     

     if(GUI.RepeatButton(Rect(10,10,200,200),"Shoot")){

         czShoot.shootOne = true;

     }

     if(GUI.Button(Rect(10,220,100,100),"Zoom")){

         if(isInScope){

             isInScope = false;

             scopeCam.SetActiveRecursively(false);

         }else if(!isInScope){

             isInScope = true;

             scopeCam.SetActiveRecursively(true);

         }

     }

 }

A script called czShoot:

 var bullets : GameObject;
 var bulletE : GameObject;
 static var shootOne : boolean = false;
 var fireDelay : float;
 var rateOfFire : float = 0.5;
 var Ammo : int = 2000;
 var bullet : Rigidbody;
 var spawn : Transform;
 var bulletShoot : AudioClip;
 
 function Update(){
 if(shootOne && Time.time > fireDelay){
     if(Ammo > 0 && canFire){
     shootOne = false;
     fireDelay = Time.time + rateOfFire;
     Instantiate(bullets, bulletE.transform.position, bulletE.transform.rotation);
     Ammo--;
     var bullet1 : Rigidbody = Instantiate(bullet, spawn.position, spawn.rotation);
     bullet1.AddForce(transform.forward * bulletSpeed);
     audio.PlayOneShot(bulletShoot);
     Destroy(bullet1.gameObject, 5);
                   }
              }
         }
 }