I believe there was a concerted effort a few years ago to re-establish the slow version. At that time the song was always started at a fast clip and accelerated at an alarming rate! It's good to hear it done at a more leisurely pace. Which tempo constitutes the "traditional" version is debatable, I suppose, but I would consider it to be the slow version. To me it brings to mind a stately, funereal street march in New Orleans - with Louis Armstrong leading the way, croaking out the verses and punctuating the song with some tasty solos on his trumpet. It's a great song to have, regardless of the tempo, but I do think it sounds better when slowed down.