Damn, this is embarrassing . I sincerely apologize If you don't understand it. I guess I need someone to write dialogues for me then.
I'll attempt to explain it. Since Marco suggested that paying the vendor a a few cents to get ice cream is quicker than threat, JR countered with the opposite of his suggestion by telling him that to threat is faster, and since faster also means 'shorter' time spent, he insulted him by comparing his size to the time spent.
Thank you for pointing that out. You just reminded me why I should be doing artworks only.