Space.Self smooth rotating menu around hand. How can I control the speed of the rotation?!?!?

Here is the script:

 using UnityEngine;
 
 public class Lerp : MonoBehaviour
 {
     [Range(0, 360)]
     public float angle = 120;//Specify Angle For Rotation
     float tempAngle;//Temporary Angle Measurement Variable
     bool horizontalFlag;//Check For Horizontal Roation
     bool isRotating;//Check Whether Currently Object is Rotating Or Not.
     int Direction;//Direction Of Rotation
 
     //Called For Initialization
     void Start()
     {
         horizontalFlag = isRotating = false;
     }
     //Method For Horizontal Input
     void CheckForHorizontalInput()
     {
         if (Input.GetAxis("Horizontal") != 0 && !isRotating)
         {
             isRotating = true;
             Direction = (Input.GetAxis("Horizontal") < 0 ? - 1 : 1);
             horizontalFlag = true;
             tempAngle = 0;
         }
     }
     //Method For horizontal Rotation
     void HorizontalRotation()
     {
         
         transform.Rotate(Vector3.back *  angle * Time.fixedDeltaTime * Direction, Space.Self);
         tempAngle += angle * Time.fixedDeltaTime;
         if (tempAngle >= angle)
         {
             tempAngle = 0;
             isRotating = false;
             horizontalFlag = false;
         }
     }
     void Update()
     {
         CheckForHorizontalInput();
         if (horizontalFlag)
             HorizontalRotation();
     }
 }