title: Lag when loading downloaded AssetBundle
body: <p>I've updated to Unity 2017.1. When I instantiate an object on scene from bundle the app freezes for 1-3 seconds. I didn't notice this problem on previous Unity version, but I don't want to downgrade to 5.6.</p>
  
  <pre><code>IEnumerator LoadAssetBundle(WWW www)
  {
      EventLisaner.Instance.SetAudioStation(false);
      while (!www.isDone)
      {
          int current = (int)(www.progress * 100);
          progressText.text = string.Format("Загрузка модели {0}%", current.ToString());
          yield return null;
      }
      yield return www;
  
      if (www.error == null)
      {
          if (bundle != null)
          {
              Destroy(destroyBundle);
              bundle.Unload(true);
  
          }
          bundle = www.assetBundle;
          StartCoroutine(InstantiationBundle());
      }
      else
      {
          loaderUI.SetActive(false);
      }
  }
  
  private IEnumerator InstantiationBundle()
  {
      GameObject inst = bundle.LoadAsset("prefab") as GameObject;
      GameObject obj = Instantiate(inst);
  
      obj.transform.SetParent(RayCam.selectObj.transform.parent, false);
      obj.AddComponent&lt;VuforiaMove&gt;();
      loaderUI.SetActive(false);
      destroyBundle = obj;
      EventLisaner.Instance.enabledLoadBundle = true;
      EventLisaner.Instance.enbledNextTrekingDonload = true;
      yield return null;
  }
  </code></pre>
  
  <p>UPD: I've determined that bug appears on this line: <code>bundle = www.assetBundle;</code>. I've tried to do <code>yield return bundle = www.assetBundle;</code> but it didn't seem to help. Still having that freeze.</p>