I agree with Ryan. As a former speaker agent, I found many speakers spoke too fast and their message was lost because you couldn't always process what they said. I call it the TLYT (talk like you are texting) phenomenon.
On the flip side, it works for certain speakers like Gary Vaynerchuk. I can't imagine him not speaking very fast. This is the exception though and not the norm. It works for Gary because he has passion in spades when he speaks.