What is the motivation? Are you forcing the other person to sit there, because pair programming is some kind of mandate? Or is that person wanting the pair session because they want to learn?
Question the motivation of the person and change process to fit, not the other way
The underlying desire to do it, of course, is to give the programmer (the one who we're investing in to improve) a chance to improve. It feels, however, like a wasted effort.
There are various ways to handle low performance, including talking to the person, finding out the reason behind the low performance. Most often it is caused by external factors.
Pair programming or any such coaching tool IMO are effective only after you dig deep into the reason behind low performance. Once the individual is ready to improve, that is when you can employ pair programming.