Ways to use less CPU?

[COLOR=#204a87]****[/COLOR]Hi guys !

I made a flash game; which is way to slow on old computers.

I’m trying to find a way to make it use less CPU; but I have some questions about all this.

-Can the CPU usage be related to the comp size ? mine is 960*830 (but the background is larger).

-Is it true that you use less CPU when setting all the unecessary items to mouseEnabled=false ?
-if I have a MC playing; but set to visible=false; is it using CPU ressources or is it ignored by the flash player ? :
I have a small SWF which loads a larger one. I put it on the stage with addChild. But what about the “main” scene (the loader) ? Should I remove the items ? Or is it enough to set them to visible=false ?

-My game uses a lot of FLV videos. For example; you can move the character with the keys. Each time you hit a key, the timeline jumps to the matching frame label. Is it OK to use FLV or is it better to use PNG sequences ?
-I heard that you can use less CPU removing all your active listeners when they’ve done what you wanted to.
I always do that, but maybe I forgot for some of them. Do you know if there is a way to list all the active listeners ?
-Any other tips or debugging tools ? how can I check the CPU usage ?

You can check the game here :

http://www.curlydraculafriends.com - login for the website is “dracula” and password is “lugosi”
when the website is loaded, click on “JOUER”.
When you have to login; use “test@test.be” as email and “test” as password.

thanks A LOT !