[plain talk]

But why do Texas politicians, such as Bush and Perry, come off so, for lack of a better word, slow, in the debates?

I find such generalizations offensive. Bush and Perry are two separate people and worlds apart. Perry speaks slower than others. That's his style. You see it as Perry not being smart but that is not necessarily the case. Perry's problem is not that he speaks slow or he is from Texas but that he doesn't come across strong in the debates. Debates aren't his thing. I think Cain and Newt are doing the best IMO.

[independent in tx]

Perry and Bush are two different people who happen to be from Texas. There are a lot of people in our state!