Ajax请求数据已缓存

I have an ajax function that loads within a setInterval as follow :

setInterval(function(){updateChart()}, 5000);

var updateChart = function(){
                    $.ajax({
                  url: './script.php',
                  type: 'post',
                  dataType: 'json',
                  cache: false,
                  data: {'candlesData':candlesData},
                  success: function(data) {
                    //alert(data);
                    //console.log("two");
                  //console.log(data);
                    gotData(data);
                    delete data;
                    delete candlesData;
                  },
                  error: function(xhr, desc, err) {
                    //console.log(xhr);
                    //console.log("Details: " + desc + "
Error:" + err);
                  }
                }).done(function() {

                });;// end ajax call 
}

My browser memory gets SIGNIFICANTLY bigger over time. I tried to diagnose and found out that the POST request in the AJAX data (candlesData) is cached everytime... You can see this in the screenshot (retained data column).

I tried everything to clear the cache but it is not working.

Snapshot of retained data