Flixel: flash game framework
flixel.org
flixel.org
Tiles however are NOT a collection of unique instances, they are blitted relatively efficiently. They do use a single instance of an empty collider to do the actual collision check, but otherwise they're pretty fast.
BUT that's not to say that flixel is not a work-in-progress with a fair number of broken or unoptimized elements :) I have a list of...oh I guess i'm down to about 20 things that have to be fixed or revised before the next big public whatever!
I think that while it could be optimize the key is that it just works. No funny tweaks involved, you can build and go and have a game without deep diving into adobe documentation.
I'm looking forward to use such a framework/engine in my upcoming multi-player Flash game. I'd be grateful if anyone here can offer me some advice/links about this.
(My impression is that Push Button Engine is more mature and probably better supported because there is a company behind it. Is that really the case?)
http://www.idevgames.com/news/object-oriented-flash-game-fra...
The only other widespread solution are Java Applets, which are better in some ways (e.g. performance) but worse in others (e.g. start-up time).