As we saw previously, thus far through his presidency Barack Obama has delivered the second-longest State of the Union speeches as measured by minutes. Bill Clinton, famously, was the most longwinded of our recent presidents.
This chart, also by Anand Katakam, shows that one reason Obama's speeches are shorter than Clinton's are simply that he talks faster:
The closest thing to a pattern I can find here is that southern presidents talk faster than northern presidents, which is especially true if you count George HW Bush as a Texan rather than a New Englander. On the other hand, even though he made Texas the base for his runs for political office, it's probably more accurate to say he's from Connecticut.