increasing float speed does nothing

hi i'm trying to increase the speed of my character controller but i can't seem to figure out how. changing the public float speed from 12 to 100 does nothing

here's what i have so far, any help would be much appreciated

 public class MoveCharacter2 : MonoBehaviour
 
 {
     public CharacterController controller;
     public float speed = 20f;
 
     // Update is called once per frame
 
     void Update()
 
     {
         float z = Input.GetAxis("Vertical");
 
         Vector3 move = Quaternion.Euler(0, Camera.main.transform.eulerAngles.y, 0) * new Vector3(0f, 0f, z * speed * Time.deltaTime);
 
         controller.Move(move * speed * Time.deltaTime);
 
     }
 
 }