Oh dear, sometimes you really need to understand the system you are critisizing before you critisize it.
Do you mean Java the language or Java the run time?
Java the language has nothing that makes it slower or faster than any other language, such as C++ or ObjC. Like all languages, a crap code = crap performance.
If you are talking about the Runtime, again, you are wrong. Firstly, Android uses the Dalvik Runtime, not Java. Since 2.2, it has used a JIT compiler, which in itself gives very much near native performance on "tight" code.
Since Android 5.0 lollipop, it has a AOT Compiler, all apps are converted to native code on installation, therefore all code is native.
Finally, your proposition that iOS is easier to port, is also very very wrong, based on the actual evidence and reality. Today, you are seeing android apps running on all types of platforms, such as windows/mac via bluestacks (http://www.bluestacks.com/) on blackberrys, and many others. IOS appas can only run NATIVELY on ios devices (even on a Mac PC it has to be compiled as an x86 app first to run on the emulator)