BitmapData even worse in Flash 9?

As a game programmer I'm interested to get out most of speed in Flash and did following test in Flash 8/9 to compare:

Draw randomly a small BitmapData with .copyPixels or .draw into another big BitmapData which is visible and covering the stage.

Flash 8:
Redraw region is same size as the small bitmap -> Fast.

Flash 9:
Redraw region is whole bitmap/stage -> Slow.

This is very annoying. Anyone know about this?

kind regards
Tomas

this is most likely due to the increased functionality of the bitmapData object in flash 9... there is quite a bit more that you can do with it this time around.