If both Clay and Nicole were answering all of the questions by picking Nicole as the Mole, then they likely could have tied, and Nicole would have been faster because she didn't have to think as much about where she was, what she wore, etc as she had lived it all, rather than just observed it.
I think if Nicole really wanted to "self-execute", then she would have slowed herself down. She is well aware of the time issue. I remember her saying in previous episodes that she makes sure to answer quickly so she won't lose if it comes down to a tie.