Hey,
I've been having trouble with performance with this game, and it turns out that the main culprit is FlxCamera.zoom property. See, my game has 16x16 sprites on a 144x256 grid, so it's impossible to see without zoom, and currently I'm using 4x which is draining performance (I've switched it to other zooms and there weren't any problems.)
So I've started looking for alternate options. Currently Flash, Windows, and Neko have either regular or fullscreen, but is there a way to change the size of the game into other resolutions, like a lot of html pages do?