Turbo Slicer cuts fast, repeatedly. In Synergy Blade we used it to slice bosses to bits on an iPad 1 at 60 FPS.
Turbo Slice includes demo scene with muffin slicing, complete with multitouch and glory trails. Add counters and game logic and have yourself a game, fast.
For more advanced work, you can call upon it directly to slice by a line in screen space, a plane as described by a triangle in world space or (for pro!) Vector4 plane equation in local space.