Adding 750 rows into Datatables rows().add() - laravel

Question

I am adding rows to a Datatable with the following code :
for (var key in itm) {
t.row.add([
null,
itm[key].itemcode,
itm[key].itemdesc,
itm[key].batch,
itm[key].expiry,
itm[key].qty,
itm[key].unit,
itm[key].rate,
itm[key].total,
itm[key].discper,
itm[key].discamt,
itm[key].staxper,
itm[key].staxamt,
itm[key].amount,
itm[key].netprate,
itm[key].salerate,
itm[key].page,
itm[key].sub1,
itm[key].sub2,
'<i class="fa fa-edit"></i>',
'<i class="fa fa-trash"></i>'
]).draw(false);
}
This is working fine except for the large data. When I try to add around 750 rows its too slow even the page hangs-up some times.
I tried to add the data using rows.add() API but its not working, the table is blank. Here is the code i am using to add bulk data.
var t = $('#productTable').DataTable();
t.rows.add(itm);
My datatable definition is as under :
$('#productTable').DataTable({
"paging": false,
"ordering": false,
"searching": false,
"info": false,
"rowHeight": '100px',
"scrollY": "200px",
"scrollX": true,
"scrollCollapse": true,
"paging": false,
"columns": [
{ data: null },
{ data: 'itemcode' },
{ data: 'itemdesc' },
{ data: 'batch' },
{ data: 'expiry' },
{ data: 'qty' },
{ data: 'unit' },
{ data: 'rate' },
{ data: 'total' },
{ data: 'discper' },
{ data: 'discamt' },
{ data: 'staxper' },
{ data: 'staxamt' },
{ data: 'amount' },
{ data: 'netprate' },
{ data: 'salerate' },
{ data: 'page' },
{ data: 'sub1' },
{ data: 'sub2' },
{ data: null },
{ data: null },],
"columnDefs": [
{ className: "dt-right", "targets": [7,8,9,10,11,12,13] },
{ "targets": varbatchcol, visible: false },
{ "targets": vardisccol, visible: false },
{ "targets": vartaxcol, visible: false },
{ "targets": vartotcol, visible: false },
{ "targets": [17,18], visible: false },
],
"fnRowCallback" : function(nRow, aData, iDisplayIndex){
$("td:first", nRow).html(iDisplayIndex +1);
return nRow;
}
});
and the data coming from server is :

Answer 1

Found the problem.
t.rows.add(itm);
should be
t.rows.add(itm).draw();
And this also solved the slow populating issue.