It's possible to hide non-business hours by setting DayPilotCalendar.HeightSpec property to HeightSpecEnum.BusinessHoursNoScroll.
However, I've already made some optimizations aimed at speeding up the rendering (will be part of
DayPilot Pro 3.8). The current snapshot can be tested in the
sandbox. The improvement is most visible on the
Vertical month view (compare with the
vertical month view that uses DayPilot Pro 3.7).