On Android, C# performs better than Java both because of language design choices (support for value types, real generic types, non-virtual method defaults) and the more mature Mono runtime compared to the relatively young Dalvik.
Is C++ good for mobile development?
Since all three, iOS, Android, and Windows, platforms support writing code in C++ , writing native code in C++ can allow reusing the code across platforms. Other than being reusable, native code written in C++ performs better and is resistant to reverse engineering.