I have a laggy camera, how do i fix it

I have a problem with my camera. Since i linked it to the upper bosy rotating its just a little laggy, it doesnt fill so smooth as before. One extra question for some reason when i start unity the camera(upperBody) starts facing upwards probably beacuse of clamp but it shouldnt.Also I imported a soldier model from blender with bones, if that helps. I will be happy for any kind of help.

public class playerLook : MonoBehaviour { public float mouseSensitivity;

 public Transform playerBody;
 public Transform upperPlayerBody;

 float xRotation;
 // Start is called before the first frame update
 void Start()
 {
     Cursor.lockState = CursorLockMode.Locked;
 }

 // Update is called once per frame
 void Update()
 {
     float mouseX = Input.GetAxis("Mouse X") * mouseSensitivity * Time.deltaTime;
     float mouseY = Input.GetAxis("Mouse Y") * mouseSensitivity * Time.deltaTime;

     xRotation -= mouseY;
     xRotation = Mathf.Clamp(xRotation, 30f, 120f);
     upperPlayerBody.transform.localEulerAngles = new Vector3(xRotation, 0f, 0f);

     playerBody.Rotate(Vector3.up * mouseX);
     upperPlayerBody.Rotate(Vector3.right * mouseY);
 }

}