bitmaps

Why is drawing bitmaps is very slow on some android 2.2 phones?

I have a simple card game where the user can drag and drop cards around the screen. On some of the 2.2 android phones like the Droid and EVO the card drawing is very slow. This is strange because it happens on some of the faster phones. However it's not all phones I test on the Droid and Droid X and the program runs great also runs good ...