WHY My Camera twitch ?????

When I play my mouse look twitch . There is my MouseLook Script : using UnityEngine; using System.Collections;

 /// Mouse Look
 /// Version 0.03
 
 [AddComponentMenu("Camera/MouseLook")]
 
 public class My_MouseLook : MonoBehaviour {
 
     [Header ("Transforms")]
     public Transform Player;
     public Transform Camera;
 
     [Header ("Rotation")]
     public float RotationByX = 0F ;
     public float RotationByY = 0F ;
 
     [Header ("Max And Min")]
     public float MaximumByY = 75F ;
     public float MinimumByY = 75F ;
 
     [Header ("Sensitivity")]
     public float SensitivityByX = 5F ;
     public float SensitivityByY = 5F ;
 
     [Header ("Smooth")]
     public float SmoothTimeByX = 5F ;//
     public float SmoothTimeByY = 5F ;//
      
     private Quaternion PlayerRotation ;
     private Quaternion CameraRotation ;
     
     void Start () 
     {
         PlayerRotation = Player.localRotation;
         CameraRotation = Camera.localRotation;
     }
     
     void Update () 
     {
         MouseLook ();
     }
     void MouseLook () 
     {
         RotationByX = Input.GetAxis ("Mouse Y") * SensitivityByY;
         RotationByY = Input.GetAxis ("Mouse X") * SensitivityByX;
         
         PlayerRotation *= Quaternion.Euler (0f, RotationByY, 0f);
         CameraRotation *= Quaternion.Euler (-RotationByX, 0f, 0f);
 
         CameraRotation = ClampRotationAroundXAxis (CameraRotation);
 
         if (RotationByY!= 0F )
         {
             Player.localRotation = Quaternion.Slerp (Player.localRotation, PlayerRotation, SmoothTimeByX * Time.deltaTime);//
         }
         if (RotationByX!= 0F )
         {
             Camera.localRotation = Quaternion.Slerp (Camera.localRotation, CameraRotation, SmoothTimeByY * Time.deltaTime);//
         }
     }
 
 
     Quaternion ClampRotationAroundXAxis(Quaternion q)
     {
         q.x /= q.w;
         q.y /= q.w;
         q.z /= q.w;
         q.w = 1.0f;
         
         float angleX = 2.0f * Mathf.Rad2Deg * Mathf.Atan (q.x);
         
         angleX = Mathf.Clamp (angleX, -MinimumByY, MaximumByY);
         
         q.x = Mathf.Tan (0.5f * Mathf.Deg2Rad * angleX);
         
         return q;
     }
 }