sets the number of 'gantt.config.duration_unit' units that will correspond to one unit of the 'duration' data property.
gantt.config.duration_unit = "hour"; gantt.config.duration_step = 3; //so if task.duration = 2, the task will long 6 hours (3*2)
If you specify the duration unit to "hour" or "minute" we recommend setting the duration_step to 1. Such combination activates certain optimizations for calculations of working time, that works only when the step is set to 1. Note, that there are major performance differences between "optimized" and "non-optimized" modes.