Well...yes. It's much heavier on the fpu (or its emulation on older devices), because it has to transform vertices of objects in question into ellipsoid space, which can be expensive on Android. What's the exact scenario in which you are using this? If it's a rather complex and huge mesh (like a level), you might want to try to use an octree for collision detection. Or you can use a alternative, simpler mesh for collision than for rendering. To do this, simply make the simple one visible and hide the complex one, do the detection and reverse the process again for rendering.