You’ll get a mixed bag in the literature:

Brake Discs — Smooth vs Drilled vs Slotted – Newparts.com

“Slotted discs are also better at heat dissipation than plain or smooth ones, and are generally on par with drilled rotors.”

“The biggest advantage of slotted rotors over drilled rotors is the fact that the former are structurally more sound. This is also why slotted brake discs are used on professional race cars.”

Drilled vs Slotted Rotors, Which is Better for You? - PowerStop Brakes

“Slotted rotors do not improve any heat transfer. However, the slots can improve brake output by removing gas and dust that is trapped between the pad and rotor. This gas and dust reduces the friction force by preventing the pad from fully contacting the rotor.”

“Given the choice between drill holes and slots, the drill holes will give you better braking power over slots for normal city/highway driving. This is why high end BMW, Porsche, Corvette, and Mercedes rotors are drilled, not slotted. However, for track racing (high speed stops), slotted rotors are the better choice.”

Just a moment...

“Slotted rotor grooves offer two distinct benefits under heavy braking: brake fade, from high-temperature brake pad outgassing, can be significantly reduced, allowing gases to escape through the slots; and the grooves shave off thin layers of brake pad material, reducing glazing and improving braking consistency.”

Thank you!

Did OP ever state what problem they're trying to solve? If it's brake fade, upgrade the brake fluid. If it's stopping power, I'd try more aggressive pads (if they exist?). But like someone else pointed out the 4Runner seems to brake pretty well all things considered, but damn is the pedal mush. I have a Porsche as a fun/track car and the pedal is rock solid, always makes for a fun first mile or two when I swap from one car to the other.

IMHO both drilled and solid rotors would introduce the ability of foreign objects (sand, mud, tiny pieces of rock, etc) to get stuck in/on the rotor and chew the pads up. They're used in track/racing applications to help dissipate heat/dust, with slotted usually being preferred due to drilled introducing weak points where cracks can/will form between holes under repeated/hard use. The drilled rotors on my Porsche definitely look cool, but they'll be replaced with slotted for peace of mind. Never seen a 4Runner on a track but I guess there's a first time for everything!

IVe run drilled and also drilled and slotted. They are great for initial bite in the rain. Where they really shine is a point of performance the 4 runner will never hit so its somewhat moot point. You can get slightly shorter stop times but this is when the normal rotors overheat and the slotted-drilled ones allow abit more use prior to fade. They are also good at removing deposits that put the rotor out of balance or give it the shudder most people incorrectly call warp

But for some applications they are quite nice, maybe with some Hawk pads to. For drilled you want them chamfered to help minimize cracks.. ive cracked a few that werent.

331K miles of experience, 250K of that with slotted on the 4Runner, lot of off-road miles including sand and mud. Sand or mud chewing up pads has never been an issue. The ceramic pads are too hard to get chewed up.

Yeah the 4R will never see a track, which is why I always get a chuckle over guys here talking about their improved high speed cornering/handling with KDSS or XREAS.