These docs are for an old release.
Info on upgrading to v5
Calendar::batchRendering
A way to group operations that cause rerenders.
calendar.batchRendering( func )
Many methods throughout the API cause rerendering of some sort, such as changeView and addEvent. If these method calls happen in quick succession, the browser will do the work of multiple rerenders but the user will only experience the final render state, which is inefficient.
To delay rerender until the last operation, you can leverage the batchRendering method:
var calendar = new Calendar(calendarEl, {
defaultView: 'timeGridWeek'
});
calendar.batchRendering(function() {
calendar.changeView('dayGridMonth');
calendar.addEvent({ title: 'new event', start: '2018-09-01' });
});
As you can see, you must pass in a function that encapsulates all of your operations.
An alternate, more implicit technique to achieve the same thing is to use rerenderDelay.