My guess is that the rotors are warped. Only an excessive amount of heat will warp the rotors. Either the piston(s) in your caliper(s) is gummed up and not releasing, the caliper slides are not moving or there is another problem in the hydraulic system causing the pads to keep too much pressure on the rotors when the brakes are released.
Slotted and drilled rotors help when there is prolonged and hard braking. They do dissipate the heat better. Before I invested in the costlier slotted/drilled rotors, I would look for the cause of the rotors warping.
Ray