C# - Raycast Bullets Object Pooling (please help)

Hello,

i have a weapon script and it is very slow- because i use Instantiate to create Bullet Holes. I searched for Object Polling and i found thinks but i dont know how to implement them into my script :( Please help me!! Heres my script- why is it so slow- could i optimize at some other points too?

  public float maxDist = 1000000000f,damage;
     public GameObject woodImpact, metalImpact, dirtImpact, concreteImpact, vegetationImpact, body, deformImpact, physmag;
     public float floatInFrontOfWall = 0.001f;
     public float fireRate = 0.5F;
     private float nextFire = 0.0F;
     private bool canfire = true, isreloading = false, isshooting = false;
     public float reloadtime;
     public AudioSource weaponsource;
     public AudioClip shotsound;
     public AudioClip reloadsound;
     public int magsize;
     public float force, deformingforce, forceoffset;
     public Transform shotcreator, magspawner;
     private int bulletsinmag;
     public float accuracy;
     [HideInInspector]
     public Quaternion originalPos;
     private Kerbo_Metal_Deform deformer;
     public Animation weaponanim;
     public float mdd;
 
 
 
 
 
 
     void Start()
     {
         bulletsinmag = magsize;
 
 
     }
 
     void FixedUpdate()
     {
         if (isreloading == false && isshooting == false)
         {
             weaponanim.CrossFade("W_Idle");
         }
         if (Input.GetButtonDown("r") && bulletsinmag < magsize)
         {
             StartCoroutine("Reload");
         }
         if (Input.GetButton("Fire1") && Time.time > nextFire && canfire == true && bulletsinmag > 0)
         {
             Fire();
         }
        
         if (bulletsinmag < 1)
         {
             StartCoroutine("Reload");
         }
 
     }
 
     IEnumerator Reload()
     {
         if (isreloading == false)
         {
             canfire = false;
             isreloading = true;
             weaponanim.CrossFade("W_Reload");
             weaponsource.clip = reloadsound;
             weaponsource.Play();
             if(bulletsinmag < 1)
             {
                 StartCoroutine("DropMag");
             }
             
             yield return new WaitForSeconds(reloadtime);
             {
                 bulletsinmag = magsize;
                
                 canfire = true;
                 isreloading = false;
 
             }
            
             yield break;
             
         }
 
     }
     
 
     void Fire()
     {
         nextFire = Time.time + fireRate;
         isshooting = true;
         originalPos = shotcreator.transform.rotation;
         RaycastHit hit;
         bulletsinmag--;
         weaponanim.Stop();
         weaponanim.Play("W_Fire");
         float randomOffset_x = Random.Range(-(0.01f - accuracy), 0.01f - accuracy);
         float randomOffset_y = Random.Range(-(0.01f - accuracy), 0.01f - accuracy);
         float randomOffset_z = Random.Range(-(0.01f - accuracy), 0.01f - accuracy);
         Vector3 direction = shotcreator.forward;
         direction.x += randomOffset_x;
         direction.y += randomOffset_y;
         direction.z += randomOffset_z;
         shotcreator.forward = direction;
         if (Physics.Raycast(shotcreator.position, shotcreator.forward, out hit, maxDist))
         {
             hit.transform.SendMessage("ApplyDamage", new Vector2(damage, 0),SendMessageOptions.DontRequireReceiver);
             if (hit.transform.GetComponent<Rigidbody>())
             {
                 hit.rigidbody.AddForceAtPosition(transform.forward * force, hit.point);
             }
 
             if (woodImpact && hit.transform.tag == "Wood")
             {
                 Instantiate(woodImpact, hit.point + (hit.normal * floatInFrontOfWall), Quaternion.LookRotation(hit.normal));
 
             }
 
             else if (body && hit.transform.tag == "Body")
             {
                 Instantiate(body, hit.point + (hit.normal * floatInFrontOfWall), Quaternion.LookRotation(hit.normal));
 
 
             }
 
             else if (concreteImpact && hit.transform.tag == "Concrete")
             {
                 Instantiate(concreteImpact, hit.point + (hit.normal * floatInFrontOfWall), Quaternion.LookRotation(hit.normal));
 
 
             }
 
 
             else if (metalImpact && hit.transform.tag == "Metal")
             {
                 Instantiate(metalImpact, hit.point + (hit.normal * floatInFrontOfWall), Quaternion.LookRotation(hit.normal));
 
 
             }
 
             else if (dirtImpact && hit.transform.tag == "Dirt")
             {
                 Instantiate(dirtImpact, hit.point + (hit.normal * floatInFrontOfWall), Quaternion.LookRotation(hit.normal));
 
             }
             else if (vegetationImpact && hit.transform.tag == "Vegetation")
             {
                 Instantiate(vegetationImpact, hit.point + (hit.normal * floatInFrontOfWall), Quaternion.LookRotation(hit.normal));
 
             }
             else if (deformImpact && hit.transform.tag == "Deformable")
             {
                 Instantiate(deformImpact, hit.point + (hit.normal * floatInFrontOfWall), Quaternion.LookRotation(hit.normal));
                 deformer = hit.collider.GetComponent<Kerbo_Metal_Deform>();
                 if (deformer)
                 {
                     Vector3 point = hit.point;
                     point += hit.normal * forceoffset;
                     deformer.AddDeformingForce(point, deformingforce);
                 }
             }
 
         }
         weaponsource.clip = shotsound;
         weaponsource.Play();
         shotcreator.rotation = originalPos;
         isshooting = false;
 
 
 
     }
     IEnumerator DropMag()
     {
         yield return new WaitForSeconds(mdd);
         Drop();
     
 
 
     }
 
     void Drop()
     {
         Instantiate(physmag, magspawner.position, magspawner.rotation);
     }

Thanks in advance!!!!

Regards, T