C++11 provides several performance and productivity enhancements over previous versions of C++. It improves performance through features like move semantics and unordered maps that prevent unnecessary copying and provide faster operations. It enhances productivity by allowing type inference with auto, easier definition of anonymous functions with lambdas, safer smart pointers that avoid memory issues, and other features that reduce visual clutter and make code intent clearer. Adopting C++11 can provide these benefits while keeping existing code that works fine unchanged.