It's very frustrating but currently C2 and large games for mobiles do not mix, that's just the simple truth.
Even if you optimize everything and use Crosswalk so it handles asset loading well, you are still bound by a 50MB APK limit, 13MB of which is taken up by the Crosswalk Chromium engine.
It's something that has to be taken into account at the start of a game development process, during development at every change or turn, etc. Anytime you add a new feature or major addition of code, you need to test on your specific devices to ensure what you added did not break something. When you work on PC, its very easy to just keep throwing more and more at it, PCs are beastly, they will run pretty much the worse unoptimized game there is. But Macs with its crap integrated intel graphics don't cut the mustard and need more care.
If you run your current game on PC, in debug, tell me whats your CPU utilization on your PC (and list its spec), I can right away know whether your game is going to be smooth on mobiles or not, based on my experience.