Agree with Ashley there. Too many people complaining about mobile performance when they clearly don't know the limitations of mobile development. Just because you can make something in C2 and can export for mobile doesn't mean that it will play well on mobile. I've learnt the hard way. Investigated what's going on under the hood, what features to use and what not to use.
X - Don't use webGl effects - They are neat but usually heavy & not useful for mobile.
X - Don't use Force own texture on layers.
X - Don't use constantly updating Text object if you can do the same with Spritefont.
X - Don't use particles, unless it's very simple and low amount of particles.
X - Don't expect heavy amount of physics to run well.
X - Don't update things every tick unless you have to. Use 'Every X Seconds'
X - Don't use big images with large areas of overlap.
* - Always limit your Top level events. The less events the the engine has to go through each tick the better.
* - Group event's and only activate groups when needed, close when not needed.
* - Use smart and cheap ways of picking objects & Structure your conditions accordingly.
* - Disable collisions for objects that don't need it. (Personally I think this should be disabled by default)
* - Keep an eye on memory, cpu, fps, draw calls, ammount of sprites, etc
* - Study and try different approaches of doing the same thing in a smarter/cheaper ways.
If your game is not performing well, it's probably not because C2, it's probably because you don't know what the hell you're doing, and have no clue what the mobile limitations are.