Lightweight Cross-platform UI

I'm currently looking for a cross-platform UI solution for a C++ game engine running on iOS, Android (NDK) and x86. I'm obviously looking for something fast and pretty lightweight, so it doesn't slow down the main render loop. Juice seems quite modular, but I'm not quite sure of the dependencies of the GUI module, how the UI elements are rendered, and how easy it would be to maintain one code base for the above platforms, etc. If someone could advise me on whether using a small subset of Juice like this would be a viable, or even good solution, that would be really helpful!

Thanks!

Hard to know what exactly what information would help.. I think there are only a handful of dependencies for the juce_gui_basic module, and it's obviously all designed to be as efficient as possible. Unless you've got more specific questions, probably the best way to see how it works internally it is just to explore the codebase.