The present invention is directed to improving the conventional high-speed cooking oven based on a combination of hot air impingement and microwave heating by providing a time-dependent spatial variation in the net air impingement and/or net microwave energy applied to the food product in the oven. This is aimed at optimizing heat transfer and microwave efficiencies in a high-speed cooking oven, thereby enabling the oven to deliver an optimal cooking efficiency in comparison to the conventional high-speed cooking oven. In addition, under the embodiments of the present invention, the cooking efficiency may be further optimized by providing a plenum between each wall of the cooking chamber and the housing of the oven.