In college I used to hold study sessions for undergraduates in computer science. One thing I found was that one-on-one interactions were incredibly simple. Bump

In college I used to hold study sessions for undergraduates in computer science. One thing I found was that one-on-one interactions were incredibly simple. Bump that up to may 5 or so people, and the mental effort to keep track of each person's reaction became more difficult. Up to about 15, almost impossible to do effectively. But, once I got past 50, it was almost like being up there by yourself. So, I can see how an introverted performer might have a similar experience as the audience grows in size.