I would suggest moving away from ZNet. It is the precursor to ZigBee and as such is clunky at best. Also, no further development is done on that firmware.
You should be able to write ZigBee (XBP24-ZB) firmware to the module and see significant improvement to the power consumption as well as faster wake up times.
One last thing, make sure all your unused I/O lines are not left floating. Either tie them high or low.