I have heard that Electrons move about a millimeter second (although electromagnetic emanations propagate at the speed of light). This is allegedly the benefit of 'optical' computing.
Not quite.[1] Propagation in most interconnects is about half the speed of light, because real-world wires have capacitance. (As low as 25% for CAT 5 cable, as high as 90% for open-wire antenna feeds.) Optical fiber runs about 70% of the speed of light. On-chip interconnects run 30%-60% of the speed of light. So there's some propagation delay improvement with optical interconnects, but it's a factor of about 2, not some huge improvement.
[1] http://www.edn.com/electronics-blogs/all-aboard-/4426188/Rul...