ทำ pagpagination แล้ว error maximum execution time of 30 seconds exceeded...

public function index($page = '1')
  {
    //initializing search condition
    $conditions = array(1);
    $publication_id = null;
    
    if($publication_id = trim($this->input->get('publication_id')))
    { 
      $conditions = array('id = ?', $publication_id);
    }
    
    $offset = ($page - 1) * $this->config->item('admin_items_per_page');
    
    $publications = Publication::all(array('conditions' => $conditions, 'order' => 'year desc', 'limit' => $this->config->item('admin_items_per_page'), 'offset' => $offset));
    
    $publications_count = Publication::count(array('conditions' => $conditions));
    

    $totalPublication = Publication::count();

    $publications_count_msg = number_format($publications_count);
    $page_msg = number_format($page);

    if($publication_id)
      $this->data['search_result'] = "พบ $publications_count_msg เอกสารเผยแพร่ จาก Keyword \"".Publication::get_title_by_id($publication_id)."\" <small> — หน้าที่ $page_msg</small>";
    else
      $this->data['search_result'] = "พบ $publications_count_msg เอกสารเผยแพร่ <small> — หน้าที่ $page_msg</small>";
    
    //set data to view
    $this->data['page'] = $page;
    $this->data['pagination'] = $this->_create_pagination($publications_count, "publications/index");
    $this->data['publications'] = $publications;
    $this->data['totalPublication'] = $totalPublication;
    $this->data['title'] = "เอกสารเผยแพร่";
    $this->data['page_styles'] = array('selectize.bootstrap3.css');
    $this->data['page_scripts'] = array('selectize.min.js');
    $this->data['inpage_script'] = 'publications/_index_js';
    $this->data['view_name'] = "publications/index";
    $this->data['view_name_sidebar'] = "publications/sidebar";
    $this->load->view('layouts/_main/index', $this->data);
  }

<div class="container">
  <div id="content">
    <div class="info">       
      <div class="clear"></div>
      <h1><i class="fa fa-file-o"></i> <span>สื่อวิชาการ</span></h1>
      <p class="researchStat">จำนวนงานวิจัยในฐานข้อมูลทั้งหมด: <?php echo $totalPublication; ?> งานวิจัย</p>
      <?php if($q = $this->input->get('q')): ?>
        <p class="researchStat"><i>แสดงผลการค้นหา '<?php echo $q; ?>' จำนวน <?php echo $numbersOfsearchResults; ?> งานวิจัย</i></p>
      <?php endif; ?>
      <h2>รายชื่องานวิจัย</h2>
      <div id="publicationLists">
        <?php foreach ($publications as $publication): ?>
        <div class="publicationBlock">
          <div class="publicationInfo">
              <!-- <span class="title">→ <a href="<?php echo base_url("publications/view/".$publication->id."?q=$q&page=$pageNum"); ?>"></a></span> -->
              <i class="fa fa-tag"></i>&nbsp;<b>หัวข้อ : </b><?php echo $publication->title;?><br>
              <i class="fa fa-user"></i>&nbsp;<b>ผู้แต่ง : </b>
                <?php if ($publication->publications_authors): ?>
                  <?php echo $publication->publications_authors->name;?>
                <?php else: ?>
                 <?php echo "ไม่ได้ระบุผู้แต่ง";?>
                <?php endif; ?><br>
              <i class="fa fa-file"></i>&nbsp;<b>ประเภทของสื่อ : </b> 
                <?php if ($publication->publication_category): ?>
                  <?php echo $publication->publication_category->name; ?>
                <?php endif; ?>
            </div>
            <div class="clear"></div>
        </div>
        <?php endforeach; ?>
        <hr>
      </div>
      <div class="clear"></div>
      <div class="paginator">
        <?php if($pageNum == 1): ?>
          <span class="start-page">← prev</span>
        <?php else: ?>
          <a class="previous" href="?page=<?php echo $pageNum-1; ?>&q=<?php echo $q; ?>">← prev</a>
        <?php endif; ?>
        <?php
          
          // calculate page number to be rendered as a link
          $listPage = 3; $listStart = -1; $listEnd = -1;
          ( $pageNum < 3*$listPage ) ? $listStart = 1 : $listStart = $pageNum - $listPage;
          if ($maxPages - $pageNum < 2*$listPage ) {
            $listEnd = $maxPages;
            if ( $maxPages - $pageNum < 2*$listPage && $pageNum > 3*$listPage ) 
              $listStart = $pageNum - ( 2*$listPage - ($maxPages - $pageNum));
          }
          else {
            if ($pageNum < 2*$listPage ) { $listEnd = 3*$listPage;}
            else $listEnd = $pageNum + $listPage;
          }
          
        ?>
        <?php for($i = $listStart; $i < $listEnd; $i++): ?>
          
        <?php if ($i == $pageNum): ?>
            <span class="selected-page"><?php echo $i; ?></span>
        <?php else: ?>
            <a href="?page=<?php echo $i; ?>&q=<?php echo $q; ?>"><?php echo $i; ?></a>
        <?php endif; ?>
          
        <?php endfor; ?>
        
        <?php if ($listEnd != $maxPages): ?>
          <span class="more">...</span>
        <?php endif; ?>
        
        <?php if($pageNum == $maxPages): ?>
          <span class="end-page">next →</span>
        <?php else: ?>
          <a class="next" href="?page=<?php echo $pageNum+1; ?>&q=<?php echo $q; ?>">next →</a>
        <?php endif; ?>
      </div>  
    </div>
  </div>
</div>

<script type="text/javascript">
<!--
/*
  $("span.summaryButton").click(function() {
    $(this).toggleClass("collapsed");
    $(this).next().toggleClass("hideText");
  });
  
  $("span.bibliographyButton").click(function() {
    $(this).toggleClass("collapsed");
    $(this).next().toggleClass("hideText");
  });
  
*/
  $("div.advance-search-button").click(function() {
    $(this).toggleClass("collapsed");
    $(this).next().toggleClass("hideText");
  });
  
  $("#year-start-select option:last-child").attr("selected", "selected");
  $(".advance-search-fields").chosen();
  $("div.advance-search-list").toggleClass("hideText");
  
  $("#publicationLists").highlight("<?php echo $q; ?>");
-->
</script>