iOS slow performance only first time

I have a performance issue the first time i play the game. After playing a scene more than 2 times, it starts working great. This performance issue happens when i move my camera. I tried using iTween first and had this problem. Then i implemented my own methods but the problem persisted. If i close my game completely and then reopen it, it does the same thing(lag the first time). My second method uses coroutines. Is there a specific place where i should be looking for improving the performance if i have this kind of problem (lag only first time)?