They don't. Although the electrical energy itself travels very quickly--some large fraction of the speed of light in most types of insulated wiring, nearly c in uninsulated wires, the electrons themselves travel very, very slowly. The speed at which they move is dependent primarly upon current and conductor cross section and is called the "drift velocity." In typical household loads and wiring, the drift velocity can be on the order of a few mm (yes, I mean millimeters) per second. In AC, they more or less just oscillate back and forth in place at the line frequency and don't really get anywhere at all.