Not sure about alpha with copyPixels... first time I used copyPixels (in my BitmapData blitting experiment), something along the lines of this happened (Photoshopped picture, couldn't be bothered to actually reproduce it):



Transparent pixels overwrote each other instead of overlaying each other. Does the copyAlpha property change that?

And yes, I'm surprised that the memory usage in the copyPixel experiment is changing so much... thought it'd just be a few bytes to store each arrow's properties, plus a few KB for the spritesheet, and maybe a few MB for the 800 x 600 BitmapData object.