Processes and systems for drilling a borehole wherein a gravitational energy term, a torsional energy term, a hydraulic energy term and a hydromechanical specific energy which is the sum thereof may be determined using real-time data and compared against corresponding setpoints. The hydraulic energy term may include a hydraulic energy reduction factor so as to account for the distance between the fluid nozzle of the drill bit and the rock and may include the kinematic viscosity of drilling fluid. One or more drilling parameters, such as weight on bit, revolutions per minute, drilling fluid flow rate, or combinations thereof, may be adjusted based upon such comparison to approximate the least amount of energy required to destroy and remove a given unit volume of rock. The setpoints may be changed manually or automatically at the direction of the user.