How would they be faster than microwave / laser terrestial towers, that already travel around the great arc?
Cables run relatively straight under the sea. If they are optic fibre, they run at a lower speed than light in vacuum.
Satellites are in space, so communicate pretty much at speed of light, but probably not in a straight line, depends where the satellites are.
HFTs are indeed great at gaming such things, will be interesting to see what happens.