I found a reference to optimizing SWC files with Flex Optimizer and I figured I would run some tests through SWF files and see what effects it had in it.

To my surprise the Optimizer tool did optimize the SWF files but just by a few bytes:

Test 1:
…_concept1_v1_alt.swf (56569 bytes)
…_concept1_v1_alt_optimized.swf (56456 bytes)

Test 2:
…600_Flash_v1.swf (38164 bytes)
…600_Flash_v1_optimized.swf (38127 bytes)

I also ran a test against a custom SWF file inside a SWC file and this is the result:

…DropDown/library.swf (14810 bytes)
…DropDown/library_optimized.swf (11723 bytes)

So the SWC files are bloated with extra information no needed and can be compressed quite a bit but SWF file no love. And it does make sense since the SWF files that I was testing contain a lot of graphics but I still gave it a go.

Here you can ind more information about Optimizing RSL SWF Files.