Have to instantiate a 9x9 of planes and its slow. What can I do to fix this?

This is missing a lot of information. You say "instantiate" in the title, but "load" in the problem description. Those are substantially different concepts. Include some code and narrow down the problem for us.

@Dave Carlile this is executed by a simple custom editor.

 using UnityEngine;
 using System.Collections;
 
 public class $$anonymous$$apGenerator : $$anonymous$$onoBehaviour {
     
     public GameObject tile;
     public GameObject floor;
     public int mapSizeX, mapSizeY;
     [Range (0, 100)]
     public int tileOutlinePercentage;
     
     public void Generate$$anonymous$$ap () {
         if (transform.FindChild ("$$anonymous$$ap"))
         {
             DestroyImmediate (transform.FindChild ("$$anonymous$$ap").gameObject);
         }
         GameObject map = new GameObject ("$$anonymous$$ap");
         map.transform.parent = transform;
         GameObject mainTile = Instantiate (floor, Vector3.zero, Quaternion.Euler (90, 0, 0)) as GameObject;
         mainTile.transform.localScale = new Vector3 (mapSizeX, mapSizeY, 0);
         mainTile.transform.parent = map.transform;
         for (int x = 0; x < mapSizeX; x ++)
         {
             for (int y = 0; y < mapSizeY; y ++)
             {
                 float mapHalfX = mapSizeX;
                 mapHalfX /= 2;
                 float mapHalfY = mapSizeY;
                 mapHalfY /= 2;
                 Vector3 tilePos = new Vector3 (x - mapHalfX + 0.5f, 0.01f, y - mapHalfY + 0.5f);
                 GameObject newTile = Instantiate (tile, tilePos, Quaternion.Euler (90, 0, 0)) as GameObject;
                 newTile.transform.localScale -= Vector3.one * tileOutlinePercentage / 100;
                 newTile.transform.parent = map.transform;
             }
         }
     }
 }