Object pulling prefabs that are randomly generating between random points?

Hello, originally i started using a generation script that is instantiating between a range of prefabs between an array of transforms. For a while it was working fine however i started using the profiler and realized this is causing a lot of problems with the cpu, it causing a lot of spikes when instantiating, and the trash manager building up. So i went into the object pooling live training video and created a basic object pooler. However, I'm still brain dead and mind boggled on how i could implement this strategy with the original script i have, and still keep it randomly spawning prefabs within the transform array. Any help or suggestions would be great. Here are the scripts.

using System.Collections; using System.Collections.Generic; using UnityEngine;

public class Generation : MonoBehaviour {

 // These are the spawn point arrays that are being used as placement for what's being spawned
 public Transform[] terrainPoints;
 public Transform[] obstaclePoints;
 public Transform[] middlePoints;
 // These are the actual list of prefabs that will be spawning
 public GameObject[] terrainSpawn;
 public GameObject[] obstacleSpawn;
 public GameObject[] middleSpawn;
 // These are the time intervals in which the spawnings will occur
 public float terrainTimer = 2;
 public float obstacleTimer = 2;
 public float middleTimer = 2;
 public float newTime = 2;
 // This is the bool that determines whether the game will be pause (this is accessed by another script, not set by this one)
 public bool isPause;
 // This is accessing the level ring of the level, this isn't set in the inspector this is set dynamically
 public GameObject theGround;

 public static Generation S;

 void Awake()
 {
     S = this;
     theGround = GameObject.Find("level ring");
 }
 
 // Update is called once per frame
 void Update () {
     // If isPause is set to false then we proceed to spawn the clones using the custom functions
     if(isPause == false)
     {
         TerrainSpawn();
         ObstacleSpawn();
         MiddleSpawn();
     }
 }
 // This is the function thats being called thats doing the spawning for terrain prefabs
 void TerrainSpawn()
 {
     // This is taking the duration of time and decreasing it by a set frame
     terrainTimer -= Time.deltaTime;
     // If this is below or equal to zero, it spawns a new clone
     if(terrainTimer <= 0)
     {
         // This randomly chooses an indexed prefab and transform and spawns something at those points
         GameObject terrainClone = Instantiate(terrainSpawn[Random.Range(0, terrainSpawn.Length)], terrainPoints[Random.Range(0, terrainPoints.Length)].transform.position, transform.rotation);
         terrainClone.transform.parent = theGround.transform;
         // This resets the duration of time for the next spawn
         terrainTimer = newTime;
     }
 }
 // This is the function called to spawn the obstacle clones
 void ObstacleSpawn()
 {
     obstacleTimer -= Time.deltaTime;
     if(obstacleTimer <= 0)
     {
         GameObject obstacleClone = Instantiate(obstacleSpawn[Random.Range(0, obstacleSpawn.Length)], obstaclePoints[Random.Range(0, obstaclePoints.Length)].transform.position, transform.rotation);
         obstacleClone.transform.parent = theGround.transform;
         obstacleTimer = newTime;
     }
 }
 // This is the function being called to spawn clones for the middle section prefabs
 void MiddleSpawn()
 {
     middleTimer -= Time.deltaTime;
     if(middleTimer <= 0)
     {
         GameObject middleClone = Instantiate(middleSpawn[Random.Range(0, middleSpawn.Length)], middlePoints[Random.Range(0, middlePoints.Length)].transform.position, transform.rotation);
         middleClone.transform.parent = theGround.transform;
         middleTimer = newTime;
     }
 }

}