3D App with 2D Overlay, performance

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http://stackoverflow.com – This is a very commented question, but I need a positive answer. I know how to draw 2D overlays in OpenGL (using Irrlicht). Now, I want to draw some GUI elements, like buttons a grid and so over. In the background, a 3D scene will be running. Ok, here goes the question. This interface (it can be moved) can be done in Java with canvas and another things. What is faster in Android 2.6, draw it by Java or in C++? Thanks. (HowTos)