Star or "Y" configuration provides the best torque at low speeds, whereas Delta produces far less torque but allows the motor to spin much faster.
If the hub is rewired using three heavy duty cross over relays, it is possible to switch between the two modes, giving you the best of both.
(Check out Doctorbass' video for more information.)You would use Star mode for pulling away and low speed torque on hills etc, and could then switch over to Delta mode as you go faster.
This should allow a much higher speed, just as a higher voltage battery will usually increase the top speed.
If the motor is producing more power and more speed, it's also going to consume more battery power in the process.
Alan