Performance While Loading Map

Hey everyone!

I'm trying to figure out why my map takes such an amazingly long time to load. I have Unity Basic, so I can't access any of the diagnostic tools I've heard about. But I just added a simple timer to the load, and it takes about 23 seconds to load. My computer isn't a wimp; what am I doing wrong, and how could I optimize this?

 function InitialGridLoadup (){
     tilePrefab = Resources.LoadAssetAtPath("Assets/Prefabs/Tile/Tile.prefab", Object);
     wallPrefab = Resources.LoadAssetAtPath("Assets/Prefabs/Tile/Wall.prefab", Object);
     ceilingPrefab = Resources.LoadAssetAtPath("Assets/Prefabs/Tile/Ceiling.prefab", Object);
     
     var timeStamp = Time.time;
     Debug.Log(timeStamp);
     
     for ( var x : int = 0; x < mapX; x++ ) {
         for ( var z : int = 0; z < mapZ; z++ ) {
             // Creates the tile
             TileArray[x, z] = new Tile(1, false, 10, x, z);
             Debug.Log(x + ", " + z);
             
         }
         Debug.Log(Time.time - timeStamp);
         yield;
     }
     
     Debug.Log(Time.time - timeStamp);
 }

 class Tile{ 
     var type : int;
     var visible : boolean = false;
     var health : int;
     var x : float;
     var z : float;
 
     
     function Tile(newType, isVisible, newHealth, newX, newZ){//constructor
         this.type = newType;
         this.visible = isVisible;
         this.health = newHealth;
         this.x = newX;
         this.z = newZ;
     }
     
     function Name() : String {return ("Tile" + x + "x" + z);}
 }

Normally, I'd also be adding the following code under the "Creates the tile" comment, which makes it go even slower.

     var tile : Transform = Instantiate(tilePrefab.transform, new Vector3(x,0,z),Quaternion.identity);

To give you an idea of what I'm doing: I'm building a tile-based map from scratch, and I'm trying to build it with good performance in mind.