My son is the same way. He can talk fast and in circles - leaves your head spinning!
I think with my son and perhaps others, it's as though by dominating the conversation they somehow think they are controlling the situation and us too.
I have learned over the years that my preferred method of communicating with my son is through private messages on Facebook. I do not like to engage in an actual talking conversation because it will always morph into some type of argument. Even in the private messages I have to be careful but at least that way I have time to truly process my response and when I've had enough I just say bye bye.
For each one of us as we journey along, we have to figure out what mode of "communication" will be best for us. A top priority for me is keeping my emotional health in check so when it comes to my son, I am always on my guard.
I love my son but I will never allow him to steal my peace of mind again.