Propagation delay for light in a semiconductor tends to be roughly equal to propagation delay for electrical signals in a semiconductor. It's not exactly equal

Propagation delay for light in a semiconductor tends to be roughly equal to propagation delay for electrical signals in a semiconductor. It's not exactly equal because the dielectric constant is a function of frequency. This is assuming you use a waveguide and travelling waves to send the electrical signals. If you charge up the whole line then, sure, that's slower.