Had a nice reply for you Paul,
An adobe article about animating objects over the (static)vector background.
As this would make the bg redraw on screen and people should use cacheAsBitmap for it.
But when i was replying,browser chrashed and all was gone.
The main issue here was the loading time and i tested with a pic(100kb) exported to swf,which becomes a png inside this swf (140kb)
onloading 50% and cpu stays around 5-15% after caching.
bitmap-traced same pic at highest settings exported as swf( 561kb)
Onloading the cpu went off the charts 100% and stays around 4-12%.
Now when applying only one frame more on the timeline or transparencies
scripting _visible or _alpha=0
This would make the vector to be redrawn.
You're right if it would be just a single static vector image
But this will in 99.9% not be the case.


Hans

pointers http://www.adobe.com/devnet/flash/ar...aching_03.html