As I understand it, all the game engine team is doing currently (apart from the usual side issues and small things to fix) is trying to stop the fps problems. That's it. No other new content. And as far as I've heard, they have had some success: the amount of players with fps problems is steadily dropping in most fansites.
Sucks to be you, but jagex are working on it and there's really very little more they can do. The people who made the squeal of fortune etc are not the same people who can fix your fps, so don't use that as an example of them wasting time before resolving the "real" issue with the game. As for the f2p stuff, well, jagex didn't want you taking pride in not giving them money, so that in my opinion is fair enough.
AS for "doubt", I'm currently enjoying the game. Still, if you aren't, then by all means quit. Just don't assume that everyone feels doubtful as well, because I'm happy about what I've done (it's been most enjoyable) and what I'm doing. The game is steadily improving, and I'm having fun while it's doing that, which is how I want things.