Loading.UpdatePreloading takes too much time in Profiler

Hello?
My unity version is 4.5.5p1 and Xcode Version is 6.1. The device that i’m testing with is iPad air with iOS 8.1.
From googling, I found very few tips about this issue. One of them was to set Application.backgroundLoadingPriority to ThreadPriority.Low when loading level asynchronously. But it didn’t solve my problem. I tried Application.LoadLevel() too, which had no effect. I wonder if anyone found the solution of it.
If you can share with it, I would really appreciate.
Thanks in advance.

http://forum.unity3d.com/threads/loading-updatepreloading-taking-up-precious-time-for-no-reason.252578/