title: Fullcalendar change background color for holidays
body: <p>Actually I use this code to set background red for holidays:</p>
  
  <pre><code>dayRender: function (dayRenderInfo) {
  
              var date = dayRenderInfo.date;
  
              var datestring = date.getFullYear() + "-" + ("0"+(date.getMonth()+1)).slice(-2) + "-" + ("0" + date.getDate()).slice(-2);
  
              var cell = dayRenderInfo.el;
  
  
  
              var array_holidays = []
  
              $.ajax({
                  type: "POST",
                  async: false,
                  dataType:"json",
                  url: "ajax/get-holidays.php",
                  data: { "anno" : date.getFullYear() },
  
                  success: function(data, status) {
  
                      array_holidays = data;
  
                  }
              });
  
              $.each( array_holidays , function( key, value ) {
  
                if ( datestring == value) {
  
                  $(cell).css("background-color", "red");
  
                }
  
              });
  
  
          },
  </code></pre>
  
  <p>I need a script cause some holidays, for example easter, change dates every year. so, get-holidays.php, give me an array of holidays based on year actually shown in calendar.</p>
  
  <p>It works great but, not very good as performance cause dayRender, in case of month view, is called 30-31 times!!!</p>
  
  <p>Any suggest to get better performance?</p>