There is a lot of conflicting information whether slotted or drilled rotors perform better than blank rotors. For a street car that will do the occasional track day, which type of rotor should I get?
I would recommend you get slotted, but not drilled rotors. Regular rotors will work fine for typical track use. What is more important is the type of brake pad you purchase to go with your disks. The reason I suggest not getting drilled rotors is, they have a tendency to crack at the holes due to stress risers. They will not last as long as you'd like them to and will not give you much more performance than just the slotted ones will. The slotted rotors will provide space for allowing brake dust and such to be brought away from the pad, which keeps it clean and better intact with the rotor.
Blank rotors have a larger area in contact with the pads than slotted or drilled rotors. Therefore they provide better braking at the same temperature.
To cool the rotor, manufacturers use a vented rotor, not a cross-drilled or slotted rotor.
cross-drilling puts holes perpendicular to the flow of air - they have no cooling effect whilst the wheel is turning.
A cross-drilled or slotted rotor has less thermal mass and thus heats up faster and fades faster.
So far as I know, with modern rotor and pad materials, dust removal is not a significant factor affecting brake performance.
I can find no scientific evidence that the resin in overheated pads outgasses faster than gas is removed by rotation. (e.g. see cross-drilled rotors myth)
What is used by people for whom performance is more important than looks?
So why do all those high dollar cars like Ferrari, Lamborghini and Porsche have drilled rotors? Well, because people think it looks cool. The rotors on those cars fail when pushed hard as well, and the professional race teams that run these cars replace them with non-drilled rotors.
Image from formula1.com The brake rotor on an F1 racing car is not cross-drilled nor slotted.
This undrilled, unslotted brake rotor stops a 100-ton vehicle from 185 MPH in 2500 feet of tarmac.
Blank rotors provide the best braking during regular operation. Slotted rotors are such because they improve performance during heavy and prolonged braking. If it were my car, I'd rather spend the money on high-heat racing pads and race-grade brake fluid (which boils at a much higher temperature).
Other things to consider are steel braided hoses and modifications to your front bumper to allow lots and lots (and lots!) of extra air to flow over your brakes to keep them cool. If you hate your car's looks enough, you could also modify the rear body panels for the same purpose. This is usually accomplished in conjunction with light alloy wheels with the thinnest spokes possible. And remember: trail-braking and heal-and-toe are your friends. Trail-braking allows you to let up off full braking earlier and heal-and-toe shifting allows the engine to slow you down a bit, while also putting you in the right gear for corner exit. These two techniques combined will simultaneously be better for your brakes AND improve your lap times.
At the end of the day, 99% drive within the rules 99% of the time. I have used all kinds of different brakes,pads & fluids. My advice? Buy good quality solid rotors and you will save a lot of money which is FAR BETTER spent on the best pads & fluid you can buy. I have a Ford Falcon V8 and redstuff pads, Penrite racing brake fluid with RDA solid rotors. After repeated hard stops, there is no fade. The solid rotors put plenty of heat into them which is how brakes work. I don't understand drilled or slotted at all as they offer nothing but negative results. Race teams use solid rotors in every class I can think of. What does that suggest?