30 seconds, does seem slow. There are several settings in Mach, that may affect this (the acceleration in the motor control section, and if it pays any attention to the servo function, possibly the 'P' term in the PID), also the delays. On mine, it is faster than this, but still takes about 15 seconds under PC control. There is obviously significant damping on this (presumably in the board, to ensure that the unit doesn't 'hunt', if a slow PWM frequency is being used). Try turning up the acceleration. Though It'll still be slower than manual, I think this may be limiting the change rate you are seeing.