At my last job (developing cross-platform mobile games for iOS & Android), we wrote our game engine in C++ with Cocos2d-X, with Lua bindings for every OS featur

At my last job (developing cross-platform mobile games for iOS & Android), we wrote our game engine in C++ with Cocos2d-X, with Lua bindings for every OS feature, such as in-app purchase, HTTP client, all Cocoas2d objects, etc. with all of the game logic written entirely in Lua. As long as you stay entirely in Lua, the performance is excellent. The only time you take a hit is when you call between Lua & C++. Generating the Lua bindings is very easy - there's a tool called ToLua++ which reads a simplified C++ header and generates the C code for the bindings.