How long did it take to walk from Nazareth to Sepphoris?

James D. G. Dunn, Jesus Remembered (Grand Rapids: Eerdmans, 2003): 298, ". . . the youthful Jesus would have (regularly?) visited Sepphoris, only two hours distant (5 km) from Nazareth by foot, perhaps even as a young carpenter assisting in the construction of its theatre." 5 km is apparently just over 3 miles, which you can walk in an hour at a stroll. Two hours would be a mile and a half an hour. Is Jimmy a slow walker?