Sounds like there is a delay in the VFD between receiving the start command and spinning up the spindle.. normally with Mach you'd feed spindle speed back in from a sensor so it knows when spindle is running... I dont know if there's a delay setting in Mach that would allow the spindle time to get up to speed before starting the cut. As to the delay on stop..well its not going to stop quickly anyway (inertia + plus I guess no braking resistor) and the run/stop command to the VFD will initiate a slow ramp down. there'll be settings on the VFD as to how fast to ramp down (as well as up btw).