Comment by momoschili

Information in an electric circuit travels along that circuit at ~0.9c. The physical light pulses that are running through the optical waveguides are more or less traveling at around ~c/n, where n is the refractive index of the material (in this case silicon, so n ~ 3.5).

the actual optical "packet" of information is traveling slower than the electric "packet". The key here is that the electric packet can a few bits, while the photonic packet in theory has a much larger bandwidth.