<div id="main">
<div id="item"></div>
.....
.
.

.
.
<div id="item"></div>

</div>

/*plugin code start*/
(function( $ ) {
$.fn.fastAppend = function(getHTML,limit){
var parent=$(this);
var str = "";
for(i=0;i<limit;i++)
{
    str = str + getHTML + "n";
}
parent.append(str);
};}( jQuery ));
/*plugin code end*/

/*Call Plugin*/
$('#main').fastAppend('<div class = "item"></div>',400);

var foo = $("<div>");
foo.append($("<div id = "item"></div>"));
foo.append($("<div id = "item"></div>"));
...
foo.append($("<div id = "item"></div>"));
$("body").append(foo);

var _sEleList = ""
for (var k=0; k < _nElements; k++) {
    _sEleList += "<div id="+ m_sPrefix+ k + " class='w_cClass'>Content</div>";
};
$('#w_oHolder').append(_sEleList);