Slowdown in Parallax

I create a Quad to use to background and have the parallax effect by script but when i play the game i have a little slowdown when the player moves. How i can resolve this? The parallax script:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class Parallax : MonoBehaviour
 {
     Material material;
     Vector2 offset;
     public Rigidbody2D rb;
 
     public float xVelocity, yVelocity;
 
     private void Awake()
     {
         material = GetComponent<Renderer>().material;
     }
 
     void Update()
     {
         offset = new Vector2(xVelocity, yVelocity);
         material.mainTextureOffset += offset * Time.deltaTime;
 
         Vector3 vel = transform.rotation * rb.velocity;
         if (vel.x > 0)
         {
             // right
             xVelocity = .1f;
         }
         else if (vel.x < 0)
         {
             // left
             xVelocity = -.1f;
         }
         else if (vel.x == 0)
         {
             xVelocity = .0f;
         }
     }