Which lead on the Z-axis?

Which lead has been tried on the z-axis so far?
What is lead on Ridgid ZR2200?
I have a SFU1204 ball screw with 4mm lead that I want to use.

The Ridgid 22000 advances 1/8 inch per turn of the screw. I sometimes wish it was a little faster. I think that if I was doing work that drove all three axes at the same time the speed would be limited by the z axis. It might be that a faster motor would be the solution to that, though.