Multilayer objects

Objects with multiple layers, even if those layers are simple shapes, become bitmaps when exported to SWF. If you're using basic shapes in object layers, consider using multiple objects on the timeline so that they can export as vectors. You can still group the objects and animate characteristics at the group level so that you can edit them as a single object. Note that this doesn't mean you should never use multilayer objects. Sometimes those objects can export and animate more efficiently than a large group of single-layer objects that would be required to achieve the same appearance.