Optimization of complex graphics

I’m making a flash game that has a lot of rather complex illustrator graphics. In the game you walk down a street, so all the graphics has to be moved every frame. In some levels where there are a lot of objects in the street the game starts to lag.

My original graphics contain a lot of layers (in illustrator). Would it help performance if I, after importing it to flash and making a mc of it, break it apart to save flash from drawing all the shapes that aren’t visible anyway?