bitmapdata.draw() memory usage

Hi!

Flash cs5 air 2

I use bitmapdata.draw method to render on the screen at 30fps. (ENTERFRAME)

What I don't uderstand is why every time i call bitmapdata.draw method inside my render function memory usage grows till GC kicks in every n. seconds (it depends on how many bitmapdata I draw)

I'm not creating anything on the fly, just drawing the same bitmapdata with a different position matrix.

Tried copypixels instead and I did NOT have that issue..

Something I don't know?

EDIT:

after some search I found that many others had that memory issue:

http://pixelpracht.wordpress.com/2010/07/06/drawing-api-memory-leak-in-flash-10-1/

http://www.ciryusnights.com/flashStuff/BmpdDrawMemoryLeak.html

I really can't believe I have to use that workaround....Adobe?