Don't forget that the AJAX update only handles SOME of the variables that can be displayed on the pages in the site.
When you turn on 'unlimited updates', it's always good to add <meta http-equiv="Refresh" content="300" />
to top.php to ensure that every 5 minutes, the browser will refresh the PHP page and get ALL the variables 'fresh'. Otherwise, you can have a mix of fresh and stale variable displays which would be confusing to your site visitors (especially in the wxtrends.php page).