Pair programming is faster than solo, in most cases …
Thursday, November 27th, 2008 
Inevitably when doing Agile XP the question is asked “Isn’t it faster to code solo than in a pair?” and typically it isn’t because most projects are like Rally Driving where you don’t know what is around the corner and you haven’t traveled the path before, and if you have this time is subtly different.
When you pair you have a navigator who reads out the pace-notes and take more notes as you go, points out dangerous obstacles ahead and ensures the maximum speed from A to B without forgetting important turns along the way.
Rarely in my experience have I seen projects where the track of development is well mapped out, smooth and repetative and where the developers do the same thing a 100 or more times, like racing solo on oval tracks NASCAR style. Of course this can happen at certain times but I’d still encourage pairing.
Pairing is useful when the problem is too big for one brain, where you want other people to learn, share knowledge and for interpersonal development. For me this means all the time.