Most of the heat capacity is in the rotor/drum. The lining is a relatively good insulator compared to the iron of the rotor, even semi and full metallic linings. The swept area of the rotor, that area the width of the pad x the circumference of the rotor, is one of the main determining factors in brake rating. The size of the caliper determines the clamping force and thus the deceleration rate that can be applied to a given gross weight. If you can clamp tighter, you can stop faster. If you have big rotors, you have more time available before overheating and you have more leverage against the turning wheel.

Mac :{)

1962 K10 short step side, much modified for rally
1969 T50 fire truck, almost nos, needs a few things