game play on veiwer is glitchy?

When I test my game on the computer is runs smooth but when I load it into my iPod or my friends iPhones it it seems to glitch. My project size is 4.4 MB, I'm using a 16 gig iPod. Any reason why this is happening?
Comments
Moving very large graphics about
Too many graphics/actors on stage
Lots of constrains
displaying text
rules fighting...
the list goes on. If you want input try to describe in more detail what you are doing in the scenes that glitch, the memory usage in the viewer, etc. then it might be possible to help more.
CHeers kipper