Preheat the oven to 350°F (175°C). In a mixing bowl, combine sliced peaches, sugar, and lemon juice. Mix well and pour into the bottom of a greased 9x13 inch baking dish.

Sprinkle the dry cake mix evenly over the peach mixture in the baking dish.

Drizzle the melted butter over the cake mix, ensuring even coverage. Sprinkle chopped pecans on top if using.

Bake in the preheated oven for 45 minutes, or until the top is golden brown and the peaches are bubbling.

Remove from oven and let cool slightly before serving.