Super Mario Bros 2D very lagging

Hello! I'm creating Super Mario Bros 2D. When I run it with 1 enemy mushroom it runs smoothly. But if enemies are more than 2 it becomes very laggy. Here is mushroom enemy script:

using System.Collections;

using System.Collections.Generic;

using UnityEngine;

public class Mushroom : MonoBehaviour

{

 public float speed;
 public bool moveLeft = true;
 public GameObject camera;
 bool colliding;
 float collidingTime;

 void Start() => Physics2D.IgnoreCollision(camera.GetComponent<BoxCollider2D>(), GetComponent<Collider2D>());

 void FixedUpdate()
 {
     if (moveLeft && GetComponent<En>().isHit == false)
         transform.Translate(Vector2.left * Time.deltaTime * speed, Space.World);
     else if (!moveLeft && GetComponent<En>**This is Enemy script**().isHit == false)
         transform.Translate(Vector2.right * Time.deltaTime * speed, Space.World);

     if (colliding)
     {
         collidingTime = 0;
     }
     else
     {
         collidingTime += Time.deltaTime;
         if (collidingTime >= 2)
             Destroy(gameObject);
     }
 }

 private void OnCollisionEnter2D(Collision2D collision)
 {
     colliding = true;

     if (!collision.gameObject.CompareTag("Player") && !collision.gameObject.CompareTag("chunk") && !collision.gameObject.CompareTag("gr"))
     {
         if (moveLeft)
             moveLeft = false;
         else
             moveLeft = true;
     }

     if (collision.gameObject.CompareTag("MainCamera"))
         Destroy(gameObject);
 }

 private void OnCollisionStay2D(Collision2D collision) => colliding = true;

 private void OnCollisionExit2D(Collision2D collision) => colliding = false;

 private void OnTriggerEnter2D(Collider2D collision)
 {
     if (collision.gameObject.CompareTag("Player"))
     {
         collision.gameObject.GetComponent<Rigidbody2D>().AddForce(Vector2.up * 3, ForceMode2D.Impulse);
         GetComponent<PolygonCollider2D>().enabled = false;
         GetComponent<En>().startDeath();
     }
 }

}

And enemy script for all enemies:

using System.Collections;

using System.Collections.Generic;

using UnityEngine;

public class En : MonoBehaviour

{

 public bool isHit = false;
 public Sprite juSp;

 private void OnCollisionEnter2D(Collision2D collision)
 {
     if (collision.gameObject.tag == "Player" && !isHit)
         collision.gameObject.GetComponent<Mario>().Lo();
 }

 public IEnumerator Death()
 {
     isHit = true;
     GetComponent<Animator>().enabled = false;
     GetComponent<SpriteRenderer>().sprite = juSp;
     if (GetComponent<Rigidbody2D>().bodyType == RigidbodyType2D.Dynamic)
         GetComponent<Rigidbody2D>().bodyType = RigidbodyType2D.Kinematic;
     if (gameObject.CompareTag("mu"))
         GetComponent<Collider2D>().enabled = false;
     yield return new WaitForSeconds(2f);
     Destroy(gameObject);
 }

 public void startDeath() => StartCoroutine(Death());

} and I have a script for when player is nearby enemies will be active:

using System.Collections;

using System.Collections.Generic;

using UnityEngine;

public class FPSOptimizer : MonoBehaviour

{

 public GameObject player;

 public GameObject[] enemy;

 void FixedUpdate()

 {

     for (int i = 0; i < enemy.Length; i++)

     {

         if (enemy[i].transform.position.x - player.transform.position.x <= 3)

             enemy[i].SetActive(true);

     }

 }

} Does anyone have idea for optimizing script? There is a lot of things to do. But I stuck there.