You could read the cell texts before sorting, so that it doesn't have to happen repeatedly in the order function:

    var rowsWithText = $tbody.find('tr').map(function() {
      return {
        row: this, 
        text: $(rowA).children('td').eq(column).text()
      };
    });
    rowsWithText.sort(function(rowA, rowB) {
        return OrderBy(rowA.text, rowB.text);
    });
    $.each(rowsWithText, function(index,row) {
        $tbody.append(row.row);
    });

You could read the cell texts before sorting, so that it doesn't have to happen repeatedly in the order function:

    var rowsWithText = $tbody.find('tr').map(function() {
      return {
        row: this, 
        text: $(this).children('td').eq(column).text()
      };
    });
    rowsWithText.sort(function(rowA, rowB) {
        return OrderBy(rowA.text, rowB.text);
    });
    $.each(rowsWithText, function(index,row) {
        $tbody.append(row.row);
    });