Motor stalling at 4000 mm/min

[dynaflux]

I have converted my machine with a AXBB-E and UCCNC. In Mach 3 the setting for X and Y stepper motors were working fine at 4000 mm/min, however in UCCNC the X motor stalls at 4000 and even at 3300 but works if set to 3000. The Y motor handled 4000 mm/min in UCCNC right from the start. What is the explanation of this?

[ger21]

What is the kernel frequency? And acceleration? In Both UCCNC and Mach3.