At the end of a complex project Adobe consultants found that the end SWF was larger that expected.
Solution
Copying the frames from the Scene into a new FLA reduced the SWF size dramatically.
Detailed explanation
Cut and paste frames into a new fla A fla file that has been used during development can produce a larger swf file than a new fla with the same frames and library objects cut and pasted into them.
This is a bug in the current Flash 8 authoring tool whereby some objects are left behind even when they are deleted from the stage and library. These objects are then compiled into the swfs. To ensure the final swf has no spurious objects cut and paste all frames and library objects into a new fla. This can be a fairly complex task but by doing this on the customer Project the swf files were reduced by between 100kB and 200kB.