title: Improve and optimize fluidity ( no lag ) of an iPhone app
body: <p>I have a ( little ) big problem with my app which is not fluid at all when I build it on my iPhone 4 ( it's perfectly fluid on iPhone 5 )..
  I made all my images lighter but nothing changes. There are no 3D or 2D animations, only "push" transitions between my views. I'm a beginner in iOS development and I think ( maybe i'm false ) that there are optimizations tips to do in the code to make the fluidity more efficient. Thank you in advance :)</p>