Free fall and transformation of object very slow on iPod Touch 4

I’m using the below script to do a papertoss kind of game. My directions and velocity are working well. But, when the object moves ( either free falls or under the influence of AddForce ), I can see a frame by frame motion of the object rather than a smooth flow.

Any idea what I’m doing wrong?

var projectile : GameObject;
var clone;

var distance: Transform;
var Prefabball : GameObject;

var elevationAngle : Vector3;
var throwForce : int;

var angle =“10”;
var force=10;
var shouldApply=false;
var touchStart: Vector3;
var touchEnd : Vector3;
var ball:GameObject;
var v:Vector3;

function Update () {
for (var i = 0; i < Input.touchCount; ++i) {

    if (Input.GetTouch(i).phase == TouchPhase.Began) {
     touchStart = Input.GetTouch(i).position;
    }
   
    else if (Input.GetTouch(i).phase == TouchPhase.Ended) {
     touchEnd=Input.GetTouch(i).position;

Launch();
}
}

}

function FixedUpdate() {

}

function Launch()
{
var p1:Vector3 = new Vector3();
var p2 :Vector3 = new Vector3();
touchStart.z = Camera.main.nearClipPlane+.1f; //push it a little passed the clip plane for camera, just to make sure its visible on screen
touchEnd.z = Camera.main.nearClipPlane+.1f;
p1 = Camera.main.ScreenToWorldPoint(touchStart);
p2 = Camera.main.ScreenToWorldPoint(touchEnd);
ball=GameObject.Find(“PaperBall”);

    v = (p2-p1);
    v.z=-1*Vector3.Distance(p2,p1);
    ball.rigidbody.AddForce(v*1000,ForceMode.Impulse);

    shouldApply=true;

}

Got this fixed. I was adding too much of lighting and I had set the render mode as ‘important’ for all this. For static objects render mode should be not important. Changed it and it works smooth.

The reason for this is mentioned here : Unity - Manual: Graphics performance fundamentals