Character Controller problem when jumping

As the title suggests, I use this script for jump with the object, but when it jumps, jump and it drops bad, jerky, not fluid, as if gravity is not added well.

public float gravity = 20.0f;
public float jumpSpeed = 8.0f;
private Vector3 movement;

void Start()
   Controller = GetComponent<CharacterController>();}

 float Horizontal = Input.GetAxis("Horizontal"); 
 float Vertical = Input.GetAxis("Vertical");
 movement = (transform.right * Horizontal + transform.forward * Vertical) * speed;

if (Controller.isGrounded && Input.GetKeyDown(KeyCode.Space)){
 movement.y = jumpSpeed;}

movement.y -= gravity * Time.deltaTime;    
 Controller.Move(movement * Time.deltaTime);

This is a different script that I have used before and know works. You need a character controller and rigidbody for it to work. This is the link to the script:

 public class example : MonoBehaviour {
     public float speed = 6.0F;
     public float jumpSpeed = 8.0F; 
     public float gravity = 20.0F;
     private Vector3 moveDirection =;
     void Update() {
         CharacterController controller = GetComponent<CharacterController>();
         // is the controller on the ground?
         if (controller.isGrounded) {
             //Feed moveDirection with input.
             moveDirection = new Vector3(Input.GetAxis("Horizontal"), 0, Input.GetAxis("Vertical"));
             moveDirection = transform.TransformDirection(moveDirection);
             //Multiply it by speed.
             moveDirection *= speed;
             if (Input.GetButton("Jump"))
                 moveDirection.y = jumpSpeed;
         //Applying gravity to the controller
         moveDirection.y -= gravity * Time.deltaTime;
         //Making the character move
         controller.Move(moveDirection * Time.deltaTime);