Word for someone that doesn't like to pause while talking

Someone who simply blathers on and on without letting anyone else get a word in edgewise is said to "monopolize the conversation".

Cambridge Dictionary Online defines "monopolize":

"to have or take complete control of something so that others are prevented from sharing it"

I believe the word you're looking for is "motormouth". According to the Cambridge online dictionary:

motormouth: noun [C] UK /ˈməʊ.tə.maʊθ/ US /ˈmoʊ.t̬ə-/

informal, disapproving

a person who talks quickly and continuously, often without considering what they are saying

Similarly, the entry for Motormouth on TVTropes provides the following definition and accompanying image:

A character who speaks if not constantly then often so quickly that it's hard to make out individual words and with the appearance of not having to stop for breath which sometimes makes it sound as though the audio track has been set to Fast Forward...

From personal experience: when I was growing up in the 80s US, the best-known motormouth was the guy who sold "micromachines" (very small model cars). I just looked him up on Wikipedia, and his name is, indeed, "Motormouth" John Moschitta.

If you didn't grow up in the 80s US, probably the first image that pops into your head when someone describes a "person who talks very quickly, without pausing" is an auctioneer ("5 dollars from the man in red now 550 from the lady in the hat do I hear six yes six from the man in red do I hear 650 do I hear 650 from the lady in the hat no? going once going twice SOOOOOLD to the man in red for fiiiive fifty!"). And indeed, it turns out an "Alberta motormouth named best auctioneer at Stampede contest".

^{As for "how to deal with them"? You should thank us for the high-bandwidth connection :)}

You might want to consider the word "blatherer", in the first sense (someone who speaks rapidly) rather than the second sense (someone who speaks incoherently).

You may also want to think about:

• "Prattler" - Someone who talks endlessly.

• "Gabbler" - Someone who gabbles (Talks rapidly and continuously).

overtalker

From urbandictionary.com: A rude person that interrupts people and speaks over them if they don't concede to being interrupted. They generally have a disregard for anything others are talking about. They are known to be loud, obnoxious, and generally inconsiderate of normal social-speaking etiquette.

Also, they will often increase their volume in order to ensure others can't interrupt.

Another option is garrulous:

excessively talkative in a rambling, roundabout manner, especially about trivial matters. _{^{Dictionary.com}}

pointlessly or annoyingly talkative _{^{Merriam Webstser}}

Given to excessive and often trivial or rambling talk; tiresomely talkative._{^{The Free Dictionary}}