Hacking read/write speed

[drtofu]

Does anyone know about the read/write speed of the japanese kingston? For ds games would a slow write speed affect the game really? What would you have to write besides the save file? The reason for these questions is that I bought the wrong micro sd card its Speed Rating: Up to 13MB/sec. read rate and up to 3.5MB/sec write rate. From looking at the japanese kingston their write speed is double mine but the read seed seems to be pretty close or so I think. Any info would be greatly appreciated.