Being on a book tour is like being on the seesaw when you're a little kid. The excitement is in having someone to play with, and in rising up in the air, but then you're at the mercy of those holding you down, and if it's your older brother, or Paul Wolfowitz, they leap up, so that you crash down and get hurt.
Whereas when you perform, the song is done. The music is out. People know it already. You can interpret it differently, the band can perform it differently, so I like the freedom of performing.