Originally Posted by knguyenk

Drilled and slotted rotors are good for dissipating heat as it prolongs brake fade or the reduction of stopping power (http://ebcbrakes.com/articles/what-is-brake-fade/) during hard and or sustained braking, which rotors can experience during tracking. That's why they are good for the track but yet are more prone to cracking (due to adding stress concentrations by drilling holes or milling slots into the rotors with repeated heating and cooling of the rotors). Selecting drilled/slotted rotors is more of a compromise for mitigating the chance of brake fade during tracking over a stronger rotor which can be more susceptible to brake fade during tracking. This is of course dependent on how one drives when they track.

Originally Posted by WylieKylie

Drilled/Slotted rotors are NOT made for dissipating heat better. Vanes built into the disks are made for directing airflow through the disks and keeping them cool. Your brakes are designed to turn kinetic energy into heat energy, speaking of standard (iron rotor) brakes, the more material you have to act as a heatsink, the better they will resist overheating. Drilling holes or cutting slots in a disk reduce the amount of material and therefore reduces the amout of heatsink. All else being equal a drilled/slotted rotor will perform worse than a blank (although the a dimpled or slotted rotor is going to remove very little material so the heat performance is going to be the same in the real world). Brake fade does happens due to heat, but it is usually an issue with the pads reaching an innefective temperature, or the brake fluid (or water in the fluid) boiling.

Way back when (decades ago) the materials used in brake pads produced gas when they got really hot, in some cases cars on a track would lose brake power because the pads produced enough gas at a high enough pressure that they would prevent the pads from touching the disk. The solution (again, decades ago) was to drill holes in the rotors to give the gas someplace to escape. This came at the cost of reducing the life of the rotors because they would crack. Not a problem in the racing world, especially since it kept the brakes working. Decades later most people still think drilled rotors means "racing" brakes. The next step in this evolution was slotted rotors, they gave the gas a place to escape and they weren't near as prone to cracking as drilled rotors. It has been a long time since brake pad manufacturers fixed the off-gassing problem. There is no performance benefit to drilled rotors, other than the looks. If anyone likes the looks of drilled rotors, look for dimpled rotors. Same look, much less prone to cracks.