Bridgeport textron Series 1 CNC

Finally got something in to the mill.

I like what I see and feel but changing direction is to rough, do I have to increase acceleration time?
What would be optimal acceleration?
I'm afraid I have to replace Z axis motor, anything over 700mm/min can cause vibration in motor and motor is losing steps when running on g-code. Playing with Z- and Z+ buttons on jogging till 1500mm/min is everything good only start and stop are little bit to rough.