Two of my characters had a large in game argument. 

Kitsune sorcerer insulted my Wayang bard a couple times, after the Wayang was called an IT and compared to a goblin, this started a fight between them, she needed more respect while his character didn't see that as being disrespectful. OOC they are fine but it took up a huge chunk of time for the session, so at what point should I step in and how can I push them forward without just saying stfu and continue?