http://www.petapixel.com/2012/06/24/dont-use-sd-cards-with-your-canon-5d-mark-iii-if-you-care-about-speed/

And Bryan saying the same thing:
http://www.the-digital-picture.com/News/News-Post.aspx?News=2595

And a table:
http://www.robgalbraith.com/bins/camera_wb_multi_page.asp?cid=6007-12452