Hi guys! I am having performance issues on my iPhone 4G in my application.

I have screen shotted the stats. Works ok on my iPad 3 but really badly on my iPhone 4G. I am not sure what is causing the lag. Ill paste my source code to see if anyone can analyse my code and identify any problems. Thanks :).

Here is my enemy controller:

pragma strict

 var enemy1Prefab : GameObject;
 var bombEnemy2Prefab : GameObject;
 var bombermanBossPrefab : GameObject;
 var eggEnemyPrefab : GameObject;
 var cat : GameObject;
 var bossToSpawn : boolean;
 var mainCamera : GameObject;
 var bombBossClip : AudioClip;
 var bombUniverseClip : AudioClip;
 var cylinder : GameObject;
 var bombBackground : Texture;
 var rainbowBackground : Texture;
 var frameCountFromStart : int;
 
 function Start () {
 bossToSpawn = true;
 }
 
 function Update () {
 frameCountFromStart++;
 
 if(Time.frameCount < 30 && Time.frameCount %2 == 0){
 Instantiate(enemy1Prefab, transform.position, transform.rotation);
 }
 
 //GameObject.FindGameObjectsWithTag("enemy").Length < 10 
 //GAME OBJECT LAYER 10 IS ENEMIES
 if(FindGameObjectsWithLayer(10).Length < 6 && Time.time > 1.0f && Time.time < 30.0f){
     var bomben : GameObject = Instantiate(enemy1Prefab, transform.position, transform.rotation) as GameObject;
     //var enemy : GameObject = Instantiate(bombermanPrefab, transform.position, transform.rotation);
 } else  if(FindGameObjectsWithLayer(10).Length < 12 && Time.time > 30.0f && Time.time < 600.0f){
     //Debug.Log("GameObject.FindGameObjectsWithTag('enemy').Length >= 4");
        var randnum : float = Random.value;
        if(randnum < 0.5){
     Instantiate(bombEnemy2Prefab, transform.position, transform.rotation);
     } else {
     Instantiate(enemy1Prefab, transform.position, transform.rotation);
     }
 }
 
 
 // GAMEOBJECT LAYER 10 IS ENEMIES
 var enemies : GameObject[] = FindGameObjectsWithLayer(10);
 
 
 
 for(var i = 0; i < enemies.length; i++){
     //Debug.Log("checking enemies"  + i);
     var eneBehaviour : enemyBehaviour = enemies[i].GetComponent(enemyBehaviour);
     //Debug.Log("health is" + eneBehaviour.health);
     if(enemies[i].transform.childCount == 0){
     Destroy(enemies[i]);
     var score : int = PlayerPrefs.GetInt("player score");
     score += 5;
     PlayerPrefs.SetInt("player score", score);
     //Debug.Log("should destroy enemies[i]");
     }
 }
 if(frameCountFromStart < 2){
 mainCamera.audio.clip = bombUniverseClip;
 mainCamera.audio.Play();
 mainCamera.audio.loop = true;
 }
 
 if(frameCountFromStart >= 2000 && bossToSpawn == true){
 
 cylinder.renderer.material.mainTexture = bombBackground;
 mainCamera.audio.clip = bombBossClip;
 mainCamera.audio.Play();
 mainCamera.audio.loop = true;
 var boss : GameObject = Instantiate(bombermanBossPrefab, transform.position, transform.rotation);
 bossToSpawn = false;
 }
 
 }
 
 function FindGameObjectsWithLayer (layer : int) : GameObject[] {
     var goArray = FindObjectsOfType(GameObject);
     var goList = new System.Collections.Generic.List.<GameObject>();
     for (var i = 0; i < goArray.Length; i++) {
        if (goArray[i].layer == layer) {
          goList.Add(goArray[i]);
        }
     }
     if (goList.Count == 0) {
        return null;
     }
     return goList.ToArray();
 }