Brake pads and rotors are always a "Hot" topic.
To understand my jest you have but to place a finger onto your brake rotor after having used your brakes.
Ok, as has been shared, follow this link for a wealth of info
My only reason is simple science, or so my old told me, Brakes work off friction, the more friction the better. The more mass on the rotor equals more friction, drilled and slotted have less mass therefore less friction ending with less stopping power, exactly how much is debatable, there are other schools of thought in OEM vs Slotted/drilled like do the slots/holes add the wear on the pads -think cheese grater
Some braking news:
in the 1960s, race teams began seeing a great loss in brake capability. In that era of organic and asbestos based pad friction material, a problem occurred with the adhesives used to fasten the pad to the steel backing plates. As the temperature of the pads increased, the adhesive would break down and cause a layer of gas to form between the rotor and the pads. That vapor layer retained heat in the rotor and acted as an “air-bearing” high-pressure area between the pad and rotor. By drilling holes in the rotor surface, those gasses were able to be dissipated into the vented center of the rotor, no longer interfering with the pad to rotor friction
However, a major function of the rotor is to transfer heat out of the brake system. The laws of Physics tell us that energy can be moved and converted to other forms of energy, but never destroyed. That means the kinetic energy (rotating mass) of the rolling wheel and tire are resisted by the brakes, which convert that motion energy into heat energy. That heat is then dissipated into the air by the cooling of the caliper body and rotor. Think of the rotor as the radiator for the brake system.
Following that heat transfer logic tells us that a rotor with more mass can absorb more heat energy than a lighter rotor of the same design. That is an advantage of larger diameter rotors, along with the greater leverage of increased size. The problem with regard to our question of drilled and slotted rotors is that those practices act to reduce the mass of the rotor, reducing the desired heat transfer. Some rodders have correctly stated that the rotor surface area is increased by drilling or slotting, but the issue in heat transfer is mass, not surface area. It does seem that a greater rotor surface area may allow a faster cool down after the heavy braking has stopped, but the issue is more about heat transfer during braking due to rotor total mass.
It is the experience based opinion of every single brake expert I have consulted, that the loss of rotor mass due to drilling and slotting creates more brake loss than any possible gains due to degassing or faster cooling of the surface area. There is no better authority on hot rod brakes than Ralph Lisena at ECI. Ralph agrees that practical street driven vehicles rarely encounter the high heat conditions that make drilled or slotted rotors beneficial from a strictly functional stand point.
To read the full article, visit this site: https://www.good-guys.com/hotnews/tr...-brake-rotors/
A general synopsis.
If you have a vehicle which will see repeated high speed braking such as a sportscar used for track day racing, there my be a benefit in drilled slotted brakes. For those of us which own a daily driver , it is unlikely we will ever heat our brakes to such a degree as to find a benefit in off-gassing our brake system.
As has been shared, for an offroad vehicle, a solid rotor with either a brake pad such as the Raybestos EHT, Wagner Thermoquiet or OEX is in my opinion your best choice.