The mobile GPU (Graphic Processing Unit) market has grown steadily due to expansion of the mobile game industry. Despite the rapid computation capability of mobile devices, handling a large amount of high-quality graphics in real-time is difficult. Therefore, effective technologies for improving mobile GPU in smartphones are required. In this thesis, we examine the trade-off between quality and performance, and address the benefits of graphic performance improvement by degrading quality. To implement this idea, we propose performance optimization methodologies for 3D applications using an OpenGL ES library hooking method. Our methodologies do not require any source code from 3D applications, and can be applied to any Android phones that use OpenGL ES in real-time. To demonstrate the benefits of our methodology, we conducted performance verifications of five well-known benchmarks using a smartphone, and measured the quality in accordance with each methodology. In addition, we showed the optimal trade-offs between quality and performance. By using the proposed technique, the performance of mobile GPU can be significantly improved to achieve a better trade-off between quality and performance.