To quote Ashley from the "Optimisation: don't waste your time" blog post:
[quote:d9gjptbb]
Our profiling has shown it's not unusual for even a fairly complex game to spend 10% of the time on the logic, and 90% of the time on rendering - even when hardware accelerated! In other words, if you're not getting 60 FPS, the #1 thing to do is think about how to speed up the drawing of the game.
If you want to use that quote, you have to get specifics, define a "fairly complex" game.
Any mobile gamedev who has used C2 on a large project knows its limitations: JS suffers a performance penalty especially on mobiles. It's also single threaded which is not good for mobile CPUs which are often made up of 4 weaker cores (imagine only ever using up to 25% of a mobile device's capability!).
Optimizations is key for mobile devs. Ignore it at your peril, then come back and make a post about why "C2 sucks for mobiles" or "C2 performance on mobiles blows donkey"... like the many threads we have on these forums on a daily basis.