Best way to travel through space... well I have this interesting idea for "warp speed" based off of Einstein's model of gravity, but I never really thought of a propulsion system. Perhaps.... no.. maybe... no... ****, I got nothing.
Why would it be slow? If you are constantly drawn forward with nothing to slow you down (i.e. air resistance) you would only pick up speed over time. You wouldn't want the CONSTANT and FIXED (in relation to the spacecrat) graviational pull to be too strong or it would tear the craft in 2 because the front (or sides or back or any combination) would accelerate too fast. This is all in theory anyway. Perhaps if we use thrusters for the enitial acceleration and only use the Gravitational pull for secondary acceleration and primary brakes.