Can't Find Optimization Problem in My Scripts

I have been trying for weeks to get my project running smoothly. It's as simple as it gets. I have set up an object pool and generator so that a few prefabs will move from right to left on the screen at random velocities. No matter what I try, I still get a lot of lag. It must be something simple that I'm missing. It's a simple 2D game with no more than 5 sprites moving at one time. It was working perfectly until a little while ago, and now for no reason it seems to lag terribly. I don't even think I changed these scripts. PLEASE if you have any idea why, let me know. Note that I have a box collider at the left edge of the screen (set as trigger) to detect when to disable the objects. I didn't include that because its obvious how it should be done.

Generator.cs

 using UnityEngine;
 using System.Collections;
 
 public class Generator : MonoBehaviour
 {
     public ObjectPooler asteroidPool;
 
     private float _createPosX;
     private float _startDelay;

     void Awake()
     {
         _createPosX = 15.0f;
         _startDelay = 1.0f;
     }
 
     void Start ()
     {
         StartCoroutine( GenerateAsteroids() );
     }
         
     IEnumerator GenerateAsteroids()
     {
         // Delay generation in the beginning of the game.
         yield return new WaitForSeconds( _startDelay );
 
         GameObject newAsteroid;
         float posY;
         float speed;
         float angVel;
 
         // Loop forever
         while( true )
         {
             // Randomize attributes of our new asteroid.
             posY = Random.Range( -5.0f, 5.0f  );
             speed = Random.Range( 3.0f, 5.0f );
             angVel = Random.Range( -50.0f, 50.0f );
 
             // Select a prefab from our object pool and set it to active.
             newAsteroid = asteroidPool.GetPooledObject();
             newAsteroid.SetActive( true ); 
 
             // Cache a reference to the new asteroid's rigidbody component.
             Rigidbody2D rb = newAsteroid.GetComponent<Rigidbody2D>();
 
             // Cache a reference to the new asteroid's transform component.
             Transform newTransform = newAsteroid.transform;
 
             // Apply the appropriate speed, position, etc. to the asteroid.
             newTransform.position = new Vector2( _createPosX, posY );
             rb.velocity = Vector2.left * speed;
             rb.angularVelocity = angVel;
 
             // Generate a new asteroid after the given amount of time.
             yield return new WaitForSeconds( 2.2f );
         }
     }
 }

ObjectPooler.cs

 using UnityEngine;
 using System.Collections;
 using System.Collections.Generic;
 
 public class ObjectPooler : MonoBehaviour
 {
     public GameObject pooledObject;
     public int pooledAmount;
 
     private List<GameObject> _pooledObjects;
     private Transform _poolerTransform;
 
     void Awake()
     {
         _pooledObjects = new List<GameObject>();
         _poolerTransform = transform;
     }
 
 
     void Start()
     {
         for( int i = 0; i < pooledAmount; i++ )
         {
             GameObject go = Instantiate( pooledObject );
             go.transform.parent = _poolerTransform;
             go.SetActive( false );
             _pooledObjects.Add( go );
         }
     }
 
     public GameObject GetPooledObject()
     {
         // Cycle through all of our pooled objects...
         for( int i = 0; i < _pooledObjects.Count; i++ )
         {
             // If we find an object in our pool that is inactive...
             if( !_pooledObjects[i].activeInHierarchy )
             {
                 // Return this game object.
                 return _pooledObjects[i];
             }
         }
 
         // If we didn't find an available object in our pool, instantiate a new one.
         GameObject go = Instantiate( pooledObject );
         go.transform.parent = _poolerTransform;
         go.SetActive( false );
         _pooledObjects.Add( go );
         return( go );
     }
 
     public void ResetPool()
     {
         foreach( GameObject go in _pooledObjects )
         {
             go.SetActive( false );
         }
     }
 }