Why does linuxcnc limit max feed rate?

I have two steppers with exactly the same parameters set up in Stepwizard.  One for the X axis and the other for the Z axis.  Identical settings on the drivers although different.  1280 microsteps per motor step and same parameters in stepwizard .  when jogging the X axis will hit 150 ipm while the Z axis will only to to 50 ipm.  these are open loop with no feedback.  The Z axis is a Swiss motor Nema 32, the X axis is a Stepperonline nema 23.  For general information the Stepperonline nema 23 with a DM556 driver is the smoothest set up I have seen.  Runs quiet and smooth.  
Just curious as to what is going on.  I'm ok with the Z axis as is as I don't run my programs too fast.  Or I could replace the motor if I need to.

Regards

post your ini file

 

Your joint and axis MAX_VELOCITY setting is
0.834856580427 for Joint2/Z Axis
and 1.66971316085 for Joint0,1 and Axis X,Y

Not sure. I'll have to look at the Stepwizard settings again or change the ini file myself. Not sure if it's something I'm doing . I'll check it out and let you know.

Thanks