The problem is your very high value of 2048 steps/mm on the Y axis. To achieve a good movement speed with that steps/mm, you will need a combination of fast electronics and firmware to generate the step pulses fast enough, and a low inductance stepper motor and at least 24V power to provide sufficient torque at high motor RPM.
Reducing microstepping will mitigate the limitation of your electronics, but not the reduction of torque at high rpm. Your best bet may be to change to either a belt drive or a leadscrew with a course pitch.
Reducing microstepping will mitigate the limitation of your electronics, but not the reduction of torque at high rpm. Your best bet may be to change to either a belt drive or a leadscrew with a course pitch.