[lambdacomplete]

This post should be titled "I made a game with ImpactJS and packaged it for iOS with phone gap" because any of the tools you used might be at fault. You said it yourself the same phone is capable of running high-end 3d games smoothly so, maybe, there is something wrong with GPU acceleration in either Impact or canvas with WKWebView. That might be the reason why Unity uses WebGL. Saying "I won't do it again" after not knowing precisely the cause of the performance issues, and just blame hybrid apps in general, is not very scientific.

[swsieber]

You're right. But its very practical - there are enough alternatives to try.