Light travels 1 foot per nanosecond in a vacuum. (Electricity in wires is slower.) A 1 GHz processor has a 1 ns cycle time. So yeah, with multi-GHz clocks the

Light travels 1 foot per nanosecond in a vacuum. (Electricity in wires is slower.) A 1 GHz processor has a 1 ns cycle time. So yeah, with multi-GHz clocks the speed of light certainly does matter a lot, and it's one reason why keeping everything on the same chip (whenever possible) is important. Parasitic capacitance and inductance and carrier transport speed are inportant too, but it's not correct to state "it has little to do with the speed of light."