Very poor performance on iPhone 4

Hi guys,
I have built a very simple 2D game with very minimal scene and I get an almost unplayable game on iPhone 4. The lag is so bad that I can't even move.
I know that iPhone 4 is outdated and has a very slow hardware, but a simple 2D game should run smoothly on it.
I tested several games that are similar to mine by other developers on the App Store and they run very smoothly on my same iPhone 4.
Anyone having this issue?
The game is also slower on iPhone 5 compared to other similar games.

 

Quality settings? On devices like ip4 you should not use msaa for example. Have you tried to set Simple or Fast quality as default quality setting for iOS target?