Who had the most knockouts in UFC?

Tough to say, it's under dispute right now. The official score clock was started late so it is considered a KO before time.

YouTube.com/watch?v=TPxkEkGUeZU">http://www.YouTube.com/watch?v=TPxkEkGUeZU

as far as I know, Chris "The Menace" Clements vs Lautaro Tucas (3 seconds) is the one. You can find videos on that one, and it really is epic!

Kid Yamamoto has a lightning quick knee that knocked a guy out between 2-4 seconds.