Frame rate drops massively when adding a second simple prefab.

I am a beginner to Unity, and am making a simple 2D game. I have a prefab sprite that the player character is trying to catch. The code for the sprite is seemingly non-complex, but when I add a second prefab to the scene, my frame rate drops from in the high hundreds to 5. Any help would be appreciated! Here is my code running on the prefab:

Code (CSharp):

1. using UnityEngine;
2.  
3. public class VictimController : MonoBehaviour
4. {
5.     public float linearSpeed = 15;
6.     public float frightAngle = 180;
7.     public int rotationArrayLength = 25;
8.     public bool debug = false;
9.     public GameObject player;
10.  
11.     private Rigidbody2D rb;
12.  
13.     private float[] rotationArray;
14.  
15.     private void Start()
16.     {
17.         rb = GetComponent<Rigidbody2D>();
18.         rotationArray = new float[rotationArrayLength];
19.     }
20.     void FixedUpdate()
21.     {
22.         //-----FIND OPTIMAL DIRECTION-----
23.         float maxLength = 0;
24.         float targetAngle = 0;
25.  
26.         //Exclude sector near player from raycasting
27.         Vector2 vectorToPlayer = player.transform.position - transform.position;
28.         float difference = Vector2.SignedAngle(Vector2.up, vectorToPlayer);
29.         float offset = difference + frightAngle / 2;
30.  
31.         //Cast out rays
32.         for (float i = offset; i < offset + (360 - frightAngle); i += 10)
33.         {
34.             RaycastHit2D hit = Physics2D.Raycast(transform.position, RotateVector2(Vector2.up, i));
35.  
36.             if (hit.collider != null)
37.             {
38.                 if(debug) Debug.DrawRay(transform.position, RotateVector2(Vector2.up * hit.distance, i), Color.red, 0f, false);
39.  
40.                 //Find the most open path and its associated angle
41.                 if (hit.distance > maxLength)
42.                 {
43.                     maxLength = hit.distance;
44.                     targetAngle = i;
45.                 }
46.             }
47.         }
48.         if (debug) Debug.DrawRay(transform.position, RotateVector2(Vector2.up * maxLength, targetAngle), Color.blue, 0f, false);
49.  
50.         rotationArray = appendArray(rotationArray, targetAngle);
51.  
52.         //-----SET ROTATION AND ADD A FORCE
53.         rb.SetRotation(arrayAverage(rotationArray));
54.         rb.AddRelativeForce(new Vector3(0f, linearSpeed, 0f));
55.     }
56.  
57.     //-----ROTATE A 2D VECTOR-----
58.     public Vector2 RotateVector2(Vector2 vector, float angle)
59.     {
60.         float theta = angle * Mathf.Deg2Rad;
61.  
62.         float cs = Mathf.Cos(theta);
63.         float sn = Mathf.Sin(theta);
64.  
65.         float x = vector.x * cs - vector.y * sn;
66.         float y = vector.x * sn + vector.y * cs;
67.  
68.         return new Vector2(x, y);
69.     }
70.  
71.     //-----ADD TO THE BEGINING OF A FLOAT ARRAY AND SHIFT THE PREVIOUS VALUES DOWN-----
72.     private float[] appendArray(float[] arr, float value)
73.     {
74.         float[] array = arr;
75.         for(int i = array.Length - 1; i > 0; i--)
76.         {
77.             array[i] = array[i - 1];
78.         }
79.  
80.         array[0] = value;
81.         return array;
82.     }
83.  
84.     //-----FIND THE AVERAGE OF AN ARRAY OF FLOATS-----
85.     private float arrayAverage(float[] arr)
86.     {
87.         float[] array = arr;
88.         float sum = 0;
89.  
90.         for(int i = 0; i < array.Length; i++)
91.         {
92.             sum += array[i];
93.         }
94.         return sum / array.Length;
95.     }
96. }
97.