The wp_list_pages() call is slow. How do I Ajax it

[eonuk]

1. ....I'm using wordpress 2.9.2
2. I am using the lifestyle theme
3. I have a LOT of pages
4. The call to the wp_list_pages (which creates menu items in the theme) is taking a long time because there are so many pages (within the div id subnavbar). As a result the page takes a long time to download
5. website is http://www.angelperfume4u.co.uk/

Is there a way I can easily make the following code in the theme a ajax call, so it is loaded after the rest of the page is loaded:

<ul id="subnav">
<?php wp_list_pages('title_li=&sort_column=post_title&de pth=2'); ?>
</ul>
</div>

website is http://www.angelperfume4u.co.uk/