It is not clear how field speed influences charges relocation speed,
If the light crossing time is not much much smaller than the circuit time constant, then the light crossing time is a significant factor in the time for the surface charge to redistribute.
Think of an RC circuit with a large decay time: the light crossing time is essentially infinitely small thus the feedback time is insignificant. For a circuit with an RC time constant that is simply larger than the light crossing time but not much much greater, the relaxation time of the circuit is limited by both the RC constant and the light crossing time thus the feedback time is significant.