title: Full Calendar slow rendering
body: <p>I'm working with a legacy codebase that uses full calendar (2.3.1) in a react based portal to display a resource view as seen in the picture attached.</p>
  
  <p>The calendar starts to get very slow whenever i move a date forwards or backwards or select a date from date picker. However this problem arises only when there are a lot of columns in resource view and when there are less columns like 4 or 5, the calendar works perfectly.</p>
  
  <p>Is there a way to improve the performance on this view? </p>
  
  <p><strong>Here's the code that initalizes the calendar:</strong></p>
  
  <pre><code>$('#calendar').fullCalendar({
      themeSystem: 'bootstrap3',
      header: false,
      events: [],
      views: {
        multiColAgendaDay: {
          type: 'multiColAgenda',
          duration: { days: 1 },
          numColumns: employees.length,
          columnHeaders: employees,
        },
      },
  
      defaultView: defaultView,
      eventMouseover: this.eventMouseover,
      //eventMouseout: this.eventMouseout,
      eventClick: props.onSelectEvent,
      nowIndicator: true,
      dayClick: this.selectTimeSlot,
      eventDrop: this.eventDrop,
      changeView: this.changeView,
      eventResize: this.eventResize,
      windowResize: this.windowResize,
      slotDuration: '00:15',
      axisFormat: 'h:mmA',
      viewRender: this.viewRender,
      allDaySlot: false,
      eventRender: this.eventRender,
      minTime: convert12To24(openingTime, 'hh:mma'),
      maxTime: convert12To24(closingTime, 'hh:mma'),
      businessHours: {
        dow: [0, 1, 2, 3, 4, 5, 6],
        start: convert12To24(openingTime, 'hh:mma'),
        end: convert12To24(closingTime, 'hh:mma'),
      },
    });
  </code></pre>
  
  <p><strong>Change View:</strong></p>
  
  <pre><code> changeView = view =&gt; {
     this.calendarComponent.fullCalendar('changeView', view);
   };
  </code></pre>
  
  <p><strong>I CAN'T CHANGE THE CURRENT CALENDAR LIBRARY AND HAVE MAKE DO WITH THIS ONLY</strong></p>
  
  <p><a href="https://i.stack.imgur.com/2IVzR.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/2IVzR.png" alt="Calendar Resource View"></a></p>