Preheat the oven to 350°F (175°C). In a mixing bowl, combine sliced peaches, sugar, and lemon juice. Stir until well mixed.

Pour the peach mixture into the bottom of a greased 9x13 inch baking dish.

Sprinkle the dry yellow cake mix evenly over the peaches.

Drizzle the melted butter over the cake mix. Sprinkle chopped pecans on top if using.

Bake in the preheated oven for 40-45 minutes, or until the top is golden brown and bubbly.

Remove from the oven and let cool for a few minutes before serving.