Actionscript 3 :: Keep Media Resources For Flash Game

We are developing an epic game using flash cs5 and actionscript 3 (no flex at all). There are lots of images and other media stuff in library that we need to use. Early i just kept them in my main .fla, but then compiling swf became very slow (more images - more time to compile). So i put all my images to filesystem outside flash, and it helps. But then some lags and bugs appeared, especially when we were testing the game on remote server. Seems like files just don't have time to load (or they loaded uncompletely) - though i did it pretty correct, sequentially, with events like onload and so on.

Finally i've created another swf with all the images and resources. I'm loading it once in my main swf and i compile it only when i need to add a new image. It works rather well, but i have feeling that i'm doing it wrong or there is another right way to organize resources more easy. Also there are some minor troubles with second swf; for example, i have to make user wait until it loads inside my first file, and if i want to run from my desktop, i always must keep these two files near in one place. And, as amount of images growth and growth, it becomes annoying to compile my 2nd swf again, even if i need to do it not so often.