Add broth and cranberry juice; simmer until mixture is reduced to 2 1/2 cups, about 8 minutes. Strain sauce into heavy medium saucepan, pressing on solids with back of spoon.
Add cranberries and sugar; boil just until berries pop, about 5 minutes.
Mix Port and cornstarch in small bowl to blend.
Add to sauce; boil until sauce thickens, about 1 minute. Season to taste with salt and pepper. (Cranberry sauce can be made 1 day ahead. Cover and refrigerate.)
Mix remaining 4 1/2 teaspoons thyme, 1 1/2 teaspoons salt, and 1 1/2 teaspoons pepper in small bowl.
Place pork in large baking dish. Pat dry with paper towel.
Brush with 2 tablespoons oil. Rub thyme mixture over pork. (Can be prepared 1 day ahead. Cover and refrigerate.)
Preheat oven to 400°F.
Heat remaining 1 tablespoon oil in heavy large ovenproof skillet over high heat.
Add pork and cook until brown, turning frequently, about 5 minutes.
Transfer skillet to oven and roast pork until instant-read thermometer inserted into thickest part of pork registers 150°F, about 20 minutes.
Transfer pork to platter; cover to keep warm.
Add cranberry sauce and remaining 1 1/2 teaspoons orange peel to same skillet and bring to simmer, stirring frequently.
Cut pork into 1/2-inch-thick diagonal slices. Divide slices among 8 plates.