Optimizing C# Code and physics

I'm trying to optimize the code for my simple jumping game and need some help identifying problem areas. My scene currently has 5 "simple" scripts. A player controller, a spawner, a remover, a control for the spawned objects and a camera follow script. Some or all of these scripts need to be optimized.

Here is a simple description of the game: Rotating balls spawn on the top of the screen and constantly move down and spin. The player jump up from ball to ball, rotating around the ball to aim for the next jump.

Here's the first script. PlayerControl: With this script I am checking in Update if the player has given an input, if so set jump to true, which is handled by FixedUpdate. I was wondering, would it be more efficient to just rename FixedUpdate to something like Jump(), and just call that function on input? Next I noticed some slow down whenever the player would collide with the falling objects, is there anything particularly inefficient or wrong with my code?

 using UnityEngine;
 using System.Collections;
 
 public class PlayerControl : MonoBehaviour 
 {
     public Sprite standCat;
     public Sprite jumpCat;
     public Sprite sitCat;
     
     public AudioClip jumpSound;
     private bool jump = false;
     private bool grounded;
     private bool isCollided = false;
     private bool waited = false;
     private int i = 0;
     private SpriteRenderer myRenderer;
     private Vector3 localDown = new Vector3(0f, 0f);
 
     // Use this for initialization
     void Awake(){
         myRenderer = gameObject.GetComponent<SpriteRenderer>();
         grounded = true;
     }
 
     // Update is called once per frame
     void Update()
     {
         //By default player has gravity set to 0. When player's velocity slows enough, set gravity to 3.
         if (this.rigidbody2D.velocity.magnitude <= 1.5f && !isCollided && this.transform.position.y > 1 && waited)
             this.rigidbody2D.gravityScale = 3f;
         i = 0;
         while (i < Input.touchCount)
         {
             if (Input.GetTouch(i).phase == TouchPhase.Began && (grounded || isCollided))
             {
                 this.collider2D.isTrigger = false;
                 waited = false;
                 this.transform.parent = null;
                 jump = true;
             }
             i++;
         }
     }
 
     void FixedUpdate()
     {
         localDown = -(this.transform.up);
         if (jump)
         {
             if (grounded)
             {
                 myRenderer.sprite = jumpCat;
                 audio.PlayOneShot(jumpSound);
                 rigidbody2D.velocity = this.transform.up * 12;
                 jump = false;
                 grounded = false;
             }
             if (isCollided)
             {
                 this.transform.Rotate(0, 0, 180);
                 myRenderer.sprite = jumpCat;
                 audio.PlayOneShot(jumpSound);
                 rigidbody2D.velocity = localDown * 12;
                 jump = false;
                 isCollided = false;
                 StartCoroutine("GravityWait");
             }
         }
     }
     IEnumerator GravityWait()
     {
         yield return new WaitForSeconds(0.75f);
         collider2D.enabled = true;
         waited = true;
     }
     
     //When player touches a ball, set ball to parent, change sprite, change up orientation,
     // set gravity and velocity to 0 and turn Collider2D into a trigger to avoid being moved when touched.
     void OnCollisionEnter2D(UnityEngine.Collision2D col)
     {
         if (this.transform.parent == null)
         {
             isCollided = true;
             this.transform.parent = col.transform;
             myRenderer.sprite = sitCat;
             this.rigidbody2D.gravityScale = 0;
             rigidbody2D.velocity = new Vector3(0, 0, 0);
             isCollided = true;
             var direction = (col.gameObject.transform.position - this.transform.position).normalized;
             this.transform.up = direction;
             this.collider2D.isTrigger = true;
         }
     }
         //If already parented, knock away balls that come in contact with player.
     void OnTriggerEnter2D(UnityEngine.Collider2D col)
     {
         var direction2 = (this.gameObject.transform.position - col.transform.position).normalized;
         col.transform.rigidbody2D.velocity = direction2 * -10f;
     }
  
 }
 

I figured I'd post the other scripts after this one gets looked at. My question might get very long if I post them all. Thanks for the help!