There's a long tradition of interest in whether certain languages or dialects are spoken faster than others. Here's probably the classic and highly accessible reference on the topic:*
Roach, Peter. 1998. Myth 18: Some languages are spoken more quickly than others. L. Bauer & P. Trudgill (eds.), Language Myths. London: Penguin. 150–158.Now, a set of news reports from Scandinavia are covering a dissertation by Anja Schüppert (Groningen, the Netherlands) showing that Danes speak far faster than Swedes. (See here for a Danish report and here for a Norwegian one — and the national perspective may differ more than the language!) The dissertation apparently finds that the difference is massive, 25-40%. I haven't tracked down the book yet, and the reports aren't too explicit, so I don't know exactly what was measured or how, but that's beyond other reports of such differences that I'm aware of. One of the interesting points (noted in the Danish report) is a possible correlations with Danish children learning to speak later than Swedish children. Gotta track down this one.
HT to LA, and that's not a city in SoCal.
*Probably as part of the "don't take us too seriously" atmosphere on this blog, we don't normally plug our own scholarship but I've been part of some work on this topic too:
Jacewicz, E., R. Allen Fox & J. Salmons. 2009. Articulation rate across dialect, gender and age. Language Variation & Change 21.233-256.