Help with physics IOS

I Have a pizza Pushing game it works like the penny pushers. It runs on ios atm but i have a problem getting the physics running smoothly(they seam to push the fps down alot)

I want the pizzas to slip off each other like they are made of ice, BUT i don't want them slipping on the table in the same way.

I have tried adding a physics materiel to pizzas like ice and then setting the table physics to none slippy but they don't seam to work, the pizzas just slip around the same like ice.

Any advice for this i am willing to listen, having already spent along time on it.

Thanks Mark