One could easily conclude that roasting would be faster because it uses a higher temperature. It also employs all three types of thermal energy: conduction, convection, and radiant heat. (Boiling and steaming use only the first two). These advantages of roasting are more than counterbalanced, however, by the fact that liquid and steam can transfer heat to food much more efficiently than air can. Moreover, as the oven temperature increases, the air expands. The increased rarefaction lessens the ability of the air in the oven to transfer heat to the roasting meat.
** Asian Recipes