Why does my device be slow after I installed an SD card?

Rate level may vary from different SD cards. It is divided into 5 levels at present, including Class2/4/6/8/10. Class10 is the highest level, whose read and write speed is fastest. Speed of reading and writing data will be affected if using SD card with low rate level, which may cause lagging. It is recommended to use the original SD card, it has already passed the tests before launching, which can meet your daily use.