SD card suddenly slow

My 3DS's sd card seems to have slowed down lately. I started noticing it when i was playing a GBA game on Rxtools, that it sometimes took a while to load stuff. I then went to Gateway, and tried a game (.3ds, Save is on SD card) and the save took a long time to load (Tried Kingdom hearts DDD, and the heart spinned about 11 times before the game finally loaded)

I never had trouble with the SD card.

(I use 2 SD cards, 1 with the saves,gateway etc, and the other for movies, clips etc.)...

SD card suddenly slow