Mobile gaming is playing an important role in the entertainment industry. Good performance is a critical requirement for mobile games in order to achieve acceptable running speed although mobile devices are limited by scarce resources. Object-oriented programming is the prevalent programming paradigm and this is true for mobile game development as well. As the origin of object-orientation (OO) is not targeting the embedded software domain, there is suspicion as to OO's usability for embedded software, especially with respect to mobile games. Questions arise like how OO and to what degree OO will affect the performance, executable file size, and how optimization strategies can improve the qualities of mobile game software. In this paper we investigate these questions within the mobile Role-Playing-Game (RPG) domain using five industrial mobile games developed with OO. We re-implemented these five RPGs with a structural programming style, by reducing the inheritance relationships, removing excessive classes and interfaces. Some additional optimizations are also applied during the re-implementation, such as the tackling of performance bottleneck methods, using more efficient algorithms. New games after optimizations run on average almost 25% faster than the corresponding original games, with a maximum of 34.62% improvement; the memory usage is decreased by more than 10% on average and 17.56% as a maximum; we also achieved a 59% code reduction and a 71% Jar file decrease after optimization. Therefore if developers are aiming for mobile game performance, we conclude that they should use as few OO features as possible. Structural programming can be a very competitive alternative.