There is the option to clear the ASO-cache:
Control->Delete ASO files.
Might help you in case you setup your bitmaps as class files
Doesn't seem that I have that option,
I have Control > Clear Publish Cache, but that doesn't reduce the file size at all.
What I usually do is import a bitmap as part of sequence, but I have to embed it in the file, rather than leave it as a reference, because I send the result over a network.
When a change is requested, I just redo the image sequence in another program and update all the bitmaps. but that causes the .fla file to get larger each time it's done.
But since I have to send it over a network, each time an update occurs it would take longer to send unless I backsave it to CS4 and delete the SWF History.
can't find much reference to SWF History anywhere else. and it apparently doesn't affect the visuals of the file.
Even if there was a setting somewhere that would prevent the compiling of this history that'd be useful as well.
Though so far I haven't discovered it.