And while buying said faster card... buy a REPUTABLE brand from a reputable vendor. I've come to the conclusion that there are a lot of fly-by-nights making cards that are not as fast as they claim to be.
Reputable vendors are companies like Sandisk and Lexar. But as an SD card is just a plastic card with a sticker on it, and stickers are pretty easy to fake, buy the card from a vendor you can trust is not selling fakes.
This is one item where it is probably not a good idea to try to save money by finding the cheapest deal you can find on the Internet.