Unity2D Choppy Slerp Update,,Rigidbody rotation choppy in update

I have been making a Flappy Bird clone, and I am having trouble with the rotation of the bird. It's very choppy with Update(). It is not choppy with FixedUpdate() in the editor, but is in the build. Here is my script (you can emulate it with a rigidbody sideways triangle):

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class BirdFly : MonoBehaviour
 {
     public GameManager gameManager;
     public float velocity = 1;
     private Rigidbody2D rb;
     public bool dead = false;
 
     public AudioSource wing;
     public AudioSource hit;
     public AudioSource die;
 
     public Animator anim;
 
     // Start is called before the first frame update
     void Start()
     {
         anim = GetComponent<Animator>();
         rb = GetComponent<Rigidbody2D>();
     }
 
     // Update is called once per frame
     void Update()
     {
         //Jump
         if (Input.GetMouseButtonDown(0) && !dead)
         {
             rb.velocity = Vector2.up * velocity;
             wing.Play();
         }
     }
 
     void FixedUpdate()
     {
         if (!dead)
         {
             //Rotate to Velocity
             //Vector2 vel = rb.velocity;
             //float ang = Mathf.Atan2(vel.y, 10) * Mathf.Rad2Deg;
             //transform.rotation = Quaternion.Euler(new Vector3(0, 0, ang * 4));
             var dir = rb.velocity;
             var angle = Mathf.Atan2(dir.y, 1.5f) * Mathf.Rad2Deg;
             var q = Quaternion.AngleAxis(angle, Vector3.forward);
             transform.rotation = Quaternion.Slerp(transform.rotation, q, 100);
         }
         
     }
 
     private void OnCollisionEnter2D(Collision2D collision)
     {
         if (!dead)
         {
             dead = true;
             rb.AddForce(Vector2.left / 2, ForceMode2D.Impulse);
             hit.Play();
             die.Play();
             anim.speed = 0;
             gameManager.GameOver();
         }
     }
 }