Since I've noticed this a few months ago already, but still can't find anything on google about this problem, and no one here seems to have the same problem or comment on this in anyway, I'm left with 3 options... either this is something that is so well knows and so common, and the solution is so simple and everyone already knows it and so everyone assumes this is some kind of a joke and they don't reply, or no one untill now has notices this problem exist or... no one is programming multiplayer games with flash anymore, so now one cares, since no one is effected...
So whats the deal here??
you could try adding this to your html (see http://help.adobe.com/en_US/as3/mobile/WS4bebcd66a74275c36cfb8137124318eebc6-7ffd.html):
<param name="hasPriority" value="true" />
i haven't looked into this new feature myself yet, so i don't know if it only applies to mobiles...
The article clearly states that:
"regardless of the value of the hasPriority parameter, a SWF file that is not visible to the user always has its rendering paused".
And this is a big big big big huge huge terrible terrible problem for programmers and users of flash based turn by turn games, since as a player, if I would want to "cheat" the game, all I need to do is simply switch to another tab in the browser, or open a new window, a program, something to cover the screen, and that would "pause" the game.
This new feature is, and will, kill the turn by turn based games, time based games (since now I can "pause" the timer) and if you think about it, real time games also, as rendering stops completely when the swf is not visible on the screen!!
This is not only ridiculous, it's going to create problems for all flash developers of real dynamic online content!!