Question 2D Game Map Editor - FPS Reduction the Longer the Game Runs

I have created a 'Custom Editor' that is used to programmatically create 'maps' that are stored as JSON files. Part of the 'map' creation process is utilizing the camera to store a snapshot. Additionally, many GameObjects are created & destroyed.

I will attempt to make 50 'maps' (create objects, move objects, take pictures of objects, delete objects, & repeat). However, as the program continues to run the FPS continues to decrease. It starts off with an FPS ~ 200, but then drops to 2-3 FPS at about 10-20 maps in.
Additionally, the "batches" in the stats starts to increase as well by double.

Another odd thing I have noticed is that if I go to the "Scene" tab & select any 2D sprite, go back to "Game" tab, and look at the FPS has jumped back up to ~ 200.

I noticed during profiling that it appears to be partially related to the "ScreenShotHandler.OnPostRender()" function (see image attached).
Note: Images are posted as reply (forums keep saying this is spam).

Is there anything wrong with the ScreenShotHandler() that could explain the drop in FPS (see Script below)?

 

Code:

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class ScreenShotHandler : MonoBehaviour
6. {
7.  
8.     private Camera myCamera;
9.     private static ScreenShotHandler instance;
10.     private bool takeScreenShotOnNextFrame;
11.     private int width, height;
12.     public float occlusion;
13.  
14.     private void Awake()
15.     {
16.         myCamera = gameObject.GetComponent<Camera>();
17.         instance = this;
18.         width = 500;
19.         height = 500;
20.     }
21.  
22.     private void OnPostRender()
23.     {
24.         if(takeScreenShotOnNextFrame)
25.         {
26.             takeScreenShotOnNextFrame = false;
27.             RenderTexture renderTexture = myCamera.targetTexture;
28.  
29.             Texture2D renderResult = new Texture2D(renderTexture.width, renderTexture.height, TextureFormat.ARGB32, false);
30.  
31.             // 8-29-2021 -- Will this prevent memory leak / fps drop?
32.             // https://forum.unity.com/threads/texture2d-destroy-how-to-do-it-right.385249/
33.             renderResult.hideFlags = HideFlags.HideAndDontSave;
34.             Rect rect = new Rect(0, 0, renderTexture.width, renderTexture.height);
35.             renderResult.ReadPixels(rect, 0, 0);
36.  
37.             float myValue = 0;
38.             float totalPixels = renderResult.width * renderResult.height;
39.  
40.             // Sum color values
41.             for (int i = 0; i < renderResult.width; i++)
42.             {
43.                 for (int j = 0; j < renderResult.height; j++)
44.                 {
45.                     Color myColor = renderResult.GetPixel(i, j);
46.                     myValue += myColor.r;
47.                     //Debug.Log("Pixel (" + i + "," + j + "): " + myColor.r);
48.                 }
49.             }
50.  
51.             occlusion = ((myValue / totalPixels) * 100);
52.  
53.  
54.             // Cleanup
55.             RenderTexture.ReleaseTemporary(renderTexture);
56.             RenderTexture.ReleaseTemporary(myCamera.targetTexture);
57.             Destroy(renderResult);
58.             myCamera.targetTexture = null;
59.             renderResult = null;
60.         }
61.     }
62.  
63.     private void TakeScreenshot(int screenWidth, int screenHeight)
64.     {
65.         width = screenWidth;
66.         height = screenHeight;
67.  
68.         if(myCamera.targetTexture != null)
69.         {
70.             RenderTexture.ReleaseTemporary(myCamera.targetTexture);
71.         }
72.  
73.         myCamera.targetTexture = RenderTexture.GetTemporary(width, height, 16);
74.         takeScreenShotOnNextFrame = true;
75.     }
76.    
77.     public static void TakeScreenshot_Static(int screenWidth, int screenHeight)
78.     {
79.         instance.TakeScreenshot(screenWidth, screenHeight);
80.     }
81. }
82.