You say speed of light in a vacuum...genius, fiber isn't a vacuum, it travels at 75% the speed as it would in a vacuum (I believe, it's closer to that). There _IS_ 70ms of latency across the US over fiber, there's no way to get around it. So your .067ms or whatever from HK is crap
Actually I believe that it is slightly lower than 75%. Given a working number of 70% (a conservative estimate) we get a time of 9.54167619 × 10^-5 s. But another limiting factor being overlooked is that light in a fiber cable does not travel in a straight line. The principle that allows a fiber cable to work is TIR, which means that the light must be constantly reflecting off of the walls of the inner cable in the fiber (there are two concentric wires with different indices of refraction), which in turn means more lag, though it is still absurdly small.