OptionZero

I'm gonna call bull on "dramatic improvement" and believe you were just experiencing a placebo effect called "new parts i bought"

Slots or holes or there for heat, not raw stopping power. Stopping shorter comes mostly from better tires, although a larger caliper/rotor can also generate more leverage. Pad compound is also a significant factor, assuming they are at the right temperature

Slotted/cross drilled also eats pads faster. And if you get cheap slotted/cross drilled rotors that are poorly made, they will be more prone to cracking. IIRC high end ones are CAST with the holes or slots in them, so they're strong; drilling afterwards can make it less structurally sound, esp if done poorly.

I'm guessing you're driving around town and dont need anything but an OEM replacement.

Nismo Z's don't come with cross drilled rotors because Nissan wants the brakes the last, and the nismo isn't are hardcore track focused as you think. It's not a GT3 or something, its a 40k sports car, not 100k.