High load

[sv3tli0]

Hello
My client posses Zen cart - 1.3.9
and his site have a big trouble.
When its opening by any browser (except Google Chrome) its generating high load - it opens 1 page per 30 seconds+...
I located the problem, and its coming by this code at main index

  require('includes/application_top.php');

  $language_page_directory = DIR_WS_LANGUAGES . $_SESSION['language'] . '/';
  $directory_array = $template->get_template_part($code_page_directory, '/^header_php/');
  foreach ($directory_array as $value) { 
/**
 * We now load header code for a given page. 
 * Page code is stored in includes/modules/pages/PAGE_NAME/directory 
 * 'header_php.php' files in that directory are loaded now.
 */
    require($code_page_directory . '/' . $value);
  } 

I understand that this FOREACH goes through a lot of files.
I am not sure from where to start .. Does any one have idea what may be the problem, or at least to tell me where to search for a problem.. (modules.. templates..)