3D circuits would be denser (shorter propagation distances) than a planar circuit. In fact "computronium" is sort of an idea about how dense you can conceptual

3D circuits would be denser (shorter propagation distances) than a planar circuit. In fact "computronium" is sort of an idea about how dense you can conceptually make computation. You just can't really cool it that well with current technologies. Microfluidics are the current magic wand that everyone wishes existed but it's a ways away yet.