13,000 is a lot of frames.
In the past (Flash 8) I was a TA, and a student was creating a Flash project that had more than 3,000 frames and it was crashing left and right. Turned out she had gone past the stable limit of the Flash 8 timeline. Since then, I know that the limit is higher, perhaps much higher, but I don't know if CS3 surpassed 10,000 frames yet, let alone 13,000.
I would break the site apart into separate SWFs and use loadMovie commands (or a Loader component) to integrate it all into one site. Doing that should help with file size as well.
Thank you, Ross! That is an advice I'll surely take into my account. Unfortunally, at this time, I can't consider such course of action because of my very tight timeframe. I'm trying to copy and paste parts of an older version into the timeline, and I hope this will holds.
But the questions remains: can I can consider, beyond any doubt, that the fact that I have an empty keyframe when it's more like a should-be-tainted-keyframe because the item is there and it appears in the end result to be a glitch from Flash? Or could I look into some other option I hadn't consider yet?
16000 is the supposed limit on frames. but there are no guarantees especially if you're already seeing problems and especially if you're using cs4.
Sorry, I forgot to mention: I'm using Flash CS3 with Actionscript 2, and exporting using Flash Player 8 option.
But thank you for giving a reference number on this case. I'll keep my fingers crossed until I end this stretch for this moment. I'll probably have to seriously consider to split apart the entire thing in the future.