In order for us to provide better support, we need to see the log generated by Citra. This guide will walk you through how you can obtain the log file: How to Upload the Log File.
Mediatec SoC’s have very bad OpenGL drivers, resulting in poor performance on OpenGL based tasks like Citra. There isn’t much we can do about this currently. Your SoC’s manufacturer needs to make better OpenGL drivers for your device to improve performance.