Scrolling

I started doing a game in flash and i went to test it.
Scrolling really lagged, droped from fps 50 to 20 whenever i scroll. So i have a few questions:

What drops the most fps when dealing with flash, because i saw a lot of games with scrolling and what not and no lag...??

How do you scroll?

I you move big layers overlapping on one another this will be slow.

I scroll normally with mouse or keyboard frame is 1600x1024
I only have 2 layers, i tried deleting one layer, i only had some interface stuff on it, and i got some fps but not much.

and actually the game now only has a map, which are tiles 64x64... could 64x64 object tiles be such a slowdown?

And to answer that, yes they can, i destroyed them all after the map was created, and pasted them as backdrops, and now there is no fps dropdown at all when scrolling.