character lagging in air when jumped

I am making a 2D game I want my 2D character to jump when button is pressed it works but it also lags for a few seconds in the air. Here's my code #pragma strict

 //For lerping
 var newPosition : Vector3 = Vector3.zero;
 var MoveDirection : Vector3 = Vector3.zero;
 var smooth = 2.0;
 
 var moveSpeed : float = 8;
 var jumpSpeed : float = 25;
 var fallSpeed : float = 64;
 var maxFallSpeed : float = 60;
 var maxUpSpeed : float = 25;
 var slopeLimit : float = 45;
 var dashSpeed : float = 120;
 var fly : boolean;
      
 private var vm : float;
 var onGround : boolean;
 private var xScale : float;
 private var h : float;
 private var v : float;
 private var jump : boolean;
 private var anim : Animator;
 private var circCollider : CircleCollider2D; //If boxCollider2D is used replace w/ ... private var boxColl : BoxCollider2D;
 
 function Awake ()
 {
     newPosition = transform.position;
 }
           
 function Start () 
 {
     xScale = transform.localScale.x; //Get correct starting Orientation for player.
     anim = gameObject.GetComponent("Animator"); //Get Animations for character
     circCollider = GetComponent(CircleCollider2D); //if boxCollider2D is used replace w/... boxColl = GetComponent(BoxCollider2D);
 }
      
 function Update () 
 {
     //h = Input.GetAxisRaw("Horizontal"); //get horizontal input
     //v = Input.GetAxisRaw("Vertical"); //get vertical input
     jump = Input.GetKey(KeyCode.Space); //get jump input
     
     //calls the lerp funtion
     LerpChanging ();
 }
      
 function FixedUpdate()
 {
     if(onGround && jump)//Are we grounded can we jump?
     { 
     vm = jumpSpeed;
     }
            
     var moveH : float = h * moveSpeed * Time.deltaTime; //Smooth horizontal movement
     //Flip character orientation
     // if(h < 0){
     //         transform.localScale.x = -xScale;
     //} else if(h > 0){
     //        transform.localScale.x = xScale;
     //}
            
     anim.SetFloat("VM", vm); //Animate VM parameter
     anim.SetBool("Grounded", onGround); //Animate Grounded parameter
     rigidbody2D.AddForce(Vector2.right * moveH); //Apply horizontal movement
     rigidbody2D.AddForce(Vector2.up * vm); //Apply vertical movement
            
     if(fly)
     { 
         //Can we fly?
         if(v > 0)
         {
         //Fly like a bird!!!
         vm += v * Time.deltaTime * 20;
         }
         else 
         {
             //Uh oh it's gravity
             vm -= fallSpeed * Time.deltaTime;
         }
     } 
     else 
         {
             //Gravity ... ouch!
             vm -= fallSpeed * Time.deltaTime;
         }
            
             vm = Mathf.Clamp(vm, -maxFallSpeed, maxUpSpeed); //Clamp vertical speeds
             rigidbody2D.velocity = Vector2.zero; //Stop movement if there is no input
             onGround = false; //Clear out grounding check
 }
      
 function OnCollisionEnter2D(c : Collision2D)
 {
     CheckCollision(c);
 }
      
 function OnCollisionStay2D(c : Collision2D)
 {
     CheckCollision(c);
 }
      
 function CheckCollision(c : Collision2D)
 {
     for(var contact in c.contacts)
     {
         //Check for floor hit
         //If boxCollider2D is used replace circCollider.radius w/ (boxCollider2D.size.y/2)
         if(vm <= 0 && contact.point.y <= transform.position.y - circCollider.radius && Vector2.Angle(Vector2.up, contact.normal) <= slopeLimit)
         {
              onGround = true;
             vm = Mathf.Max(0, vm);
         }
     }
 }
 
 function LerpChanging ()
 {
     //variable for the lane system
     var positionA : Vector3 = new Vector3(-47, -6, -10);
     var positionB : Vector3 = new Vector3(-47, -12, -10);
         
     //move the character in 4 lane
     if(Input.GetKeyDown(KeyCode.Q))
     {
         newPosition = positionA;
     }
     if(Input.GetKeyDown(KeyCode.E))
     {
         newPosition = positionB;
     }
     
     transform.position = Vector3.Lerp(transform.position, newPosition, Time.deltaTime * smooth);
 }