Extending MovieClip and Performance

Hi, we are looking at a flash program that runs very slowly or stops completely and times out. It draws a map dynamically in Flash. It loads data from the Server via XML. The size of XML is about 60k and is stored in memory after parsing it. As it parses the XML, it instanciates map objects (street/road sign & text) and attaches movieclips. It creates around 50-400 movieclips per map. It slows down when there are over 250 mc’s and we are investigating why and need help. All of the users of the application have broadband so download speed is not an issue.

The size of the flash document is 1000 X 1000, but the actual map area is 360 x 270. Each sign is 40 x 30. It also downloads the background image in png (50-250k) and a headline image in png (34K).

Everything in the map is an object, defined in a .as class. But, these classes are subclasses of MovieClip class, ie “class RoadSign extends MovieClip”. Most of the road signs/street labels are invisible, until the user make them visible. These map classes are pretty big. Their .as files about 10 - 30k

So, we are thinking about decoupling the moviceclips from the business objects and dynamically attach movieclips when they are visible and remove them when not. Will this approach improve the performance?

Does anyone know what the performance impact of storing XML in memory? Also, how does the dimension of the document impact performance in general? Could the size of the bg image and the headline image impact performance?

Thanks for your help in advance.