It's designed specifically for mobiles.
And I test everytime I add some new feature to make sure I optimize it as much as possible. So far its running 60 fps solid on my LG G-Pad 8.3 with S600 (slightly weaker than Nexus 7 with S4 Pro and about 30-40% weaker than newer devices such as S5 and Z2), and get dips to 40fps with my Tegra 3 tablet (T3 is pretty crap for html5 & java), still perfectly playable. I'm aiming for 30 fps limit on older devices. So far its holding up very well, extremely impressed with how fast C2 games can run on mobiles actually!
Well I don't know how else to draw characters except for manga/comic style. It's like the only style I can do lol.