There's nothing magical about it. As has been pointed out, chips with superconductors has been a thing for a long time (at least in experimental physics) and th

There's nothing magical about it. As has been pointed out, chips with superconductors has been a thing for a long time (at least in experimental physics) and there's nothing magical about it, but resistivity is a (nonlinear) function of temperature and lowering it almost always lowers the resistance, so you can achieve this to an extent even with non "magical" materials without going to cryogenic temperatures. You don't have to reduce the capacitance; you'll be fine as long as you can lower the resistivity. Do you have any references for FETs that switch at 10THz? I've never heard of it and I'm interested in the physics of it.