JQGRID Performance issues - performance

Question

My Jqgrid is freezing after 500 rows, page is blocking and if rows exceeds 1000 or 1500 then one browser alert is coming and saying that "long time to execute script .. do you wanna stop or continue.. " I am in no mans land can you please check my code and suggest me.. Am I doing any wrong.
one more issue is Why my loading GIF image and page stuck until all rows loaded?
$(document).ready(function ()
{
GetTrackOrdersData();
});
var searchFilter = {};
searchFilter.REFERENCE = "%";
searchFilter.INVOICENOR = "";
searchFilter.PRODNAME = "ALL";
searchFilter.ORDSTATUS = "WIP";
------etc ------
function GetTrackOrdersData()
{
var param = JSON.stringify(
{
'searchFilter': searchFilter
}); //This function is from JSon2.js
$.ajax(
{
type: "POST",
url: "TrackOrdersNew.aspx/GetTrackOrdersData",
data: param,
contentType: "application/json; charset=utf-8",
dataType: "json",
success: function (mydata)
{debugger;
var mydata = $.parseJSON(mydata.d);
if (mydata != null && mydata.length == 0)
{
$('#divgrid').hide();
$('#gbox_list1').hide();
$("#jqgridWrapperdiv").hide();
alert('No Records');
}
else if(mydata != null)
{
var i = 0;
for (i; i <= mydata.length; i++)
{
jQuery("#list1").jqGrid('addRowData', i + 1, mydata[i]);
}
if (i > 0)
{
$('.ui-jqgrid-title').text('Track Orders (' + (i - 1) + ')');
}
$("#jqgridWrapperdiv").hide();
$('#divgrid').show();
}
},
error: function (mydata)
{
alert("Some thing went wrong because of network. Please reload the page. Code:100T"+mydata.responseText);
$('#divgrid').hide();
},
complete: function ()
{
$("#jqgridWrapperdiv").hide();
}
});
}
function bindGrid()
{
jQuery("#list1").jqGrid(
{
datatype: "local",
colNames: ['Customer', 'Delivery', 'TrackNo','Ref', 'JobNo', 'Type', 'Product', 'Status',
'EntryDate', 'Scheduled', 'Invoiced'
],
colModel: [
{
name: 'CUOH_CUST_CD',
index: 'CUOH_CUST_CD',
width: 100,
classes: 'pointer'
},
{
name: 'CUOA_DEL_CUST_CD',
index: 'CUOA_DEL_CUST_CD',
width: 69,
classes: 'pointer'
},
{
name: 'CUOH_TRAK_NO',
index: 'CUOH_TRAK_NO',
width: 70,
classes: 'pointer'
},
{
name: 'CUOH_SOURCE_REF',
index: 'CUOH_SOURCE_REF',
width: 70,
classes: 'pointer'
},
{
name: 'CUOH_JOB_NO',
index: 'CUOH_JOB_NO',
width: 60,
classes: 'pointer'
},
{
name: 'CUOH_ORDER_TYPE',
index: 'CUOH_ORDER_TYPE',
width: 65,
classes: 'pointer'
},
{
name: 'CUOL_DESCR_LOC',
index: 'CUOL_DESCR_LOC',
width: 155,
classes: 'pointer'
},
{
name: 'Status',
index: 'Status',
width: 100,
classes: 'pointer',
cellattr: function (rowId, value)
{
// additional parameter of cellattr: rawObject, cm, rdata are optional
if (value.indexOf("ompleted")!=-1)
{
return ' class="bcolor"';
}
}
},
{
name: 'CUOH_ENTRY_DATE_TIME',
index: 'CUOH_ENTRY_DATE_TIME',
formatter: 'date',
formatoptions:
{
srcformat: 'd/m/Y',
newformat: 'd/m/Y'
},
width: 77,
classes: 'pointer'
},
{
name: 'CUOH_SCHEDULE_DATE',
index: 'CUOH_SCHEDULE_DATE',
formatter: 'date',
formatoptions:
{
srcformat: 'd/m/Y',
newformat: 'd/m/Y'
},
width: 84,
classes: 'pointer'
},
{
name: 'CUOH_INVOICE_DATE_TIME',
index: 'CUOH_INVOICE_DATE_TIME',
formatter: 'date',
formatoptions:
{
srcformat: 'd/m/Y',
newformat: 'd/m/Y'
},
width: 72,
classes: 'pointer'
}],
//multiselect: true,
//rowList: [10, 20, 30, 40],
//pager: jQuery('#pager1'),
//rowList: [], // disable page size dropdown
//pgbuttons: false, // disable page control like next, back button
//pgtext: null, // disable pager text like 'Page 0 of 10'
//viewrecords: true, // disable current view record text like 'View 1-10 of 100'
rowNum: 10000,
sortorder: "asc",
caption: "Track Orders",
gridview: true,
//shrinkToFit: true,
loadui:"block",
loadonce: true,
rownumbers: true, //Displays Row number Column
onSelectRow: function (rowId)//ondblClickRow
{
var rowData = jQuery(this).getRowData(rowId);
var trackingNo = rowData['CUOH_TRAK_NO'];
RowClicked(trackingNo);
}
});
}
C sharp:
[WebMethod(EnableSession = true)]
[ScriptMethod(ResponseFormat = ResponseFormat.Json)]
public static string GetTrackOrdersData(TrackOrdersFilterData searchFilter)
{
if (HttpContext.Current.Session["LoginName"] == null)
{
HttpContext.Current.Response.Redirect("~/Login.aspx");
}
string val = string.Empty;
DataSet ds = GetTrackOrders(searchFilter);
if (ds.Tables.Count > 0)
{
val = DataTableToJSON(ds.Tables[0]);
}
return val;
}