AS lightweight?

Does using actionscript descrease the size of a file as compared to working with the timeline?
For example, would using AS to cause a graphic to fade away be more effecient (as far as file size and performance) than using a symbol effect or even changing the alpha frame by frame?
I know this is a stupid question. But I’ve been using flash for a year now. I’ve never learned AS because I thought I could do everything from the timeline. But my files always seem so large. And most animation effects seem choppy in comparison with what I see online. Is AS the key to changing that?