WordPress hanging while logged in

For several years, my WordPress has had intermittent problems with hanging while I am logged in – this affects loading admin screens and published parts of the blog. The request will take minutes to be acted upon, then retrieve no content – for example, an admin screen will display that says there are no posts or pages, and similarly a post or index screen will show with the themes, heading etc but no content, including the title. This does not affect when I am not logged in (for example, using a Chrome incognito window), does not affect XML-RPC requests (e.g. WordPress for Android or my custom blog posting app QTM), and it does not affect other sites I am running on the same host using Drupal. The problem strikes suddenly – after working fine – lasts about fifteen to thirty minutes and can occur at least once daily.

I am using the Weaver II theme and the following plugins are active (latest version unless otherwise stated):

– Akismet
– Breadcrumb NavXT
– Brian’s Latest Comments (just deactivated this as I am using Disqus)
– Broken Link Checker
– Clever Tweet (just deactivated)
– Custom Post Type UI
– Disqus Comment System
– Do Follow (Version 4.0)
– Fast Secure Comment Form
– Fidgetr (just deactivated)
– Jetpack
– Link Within
– My Link Order
– No Frames (version 0.2)
– Possibly Related Recent Posts (version 1.2)
– Search Everything
– Share Buttons by Lockerz / AddToAny
– Simple Twitter Connect – Base
– STC – Follow Button Widget
– STC – Publish
– Subscribe To Comments
– Tabbed Widgets (not using, will deactivate)
– Text Control (version 2.2.3)
– URL Shortener
– WP-PageNavi

In the past, this problem has been solved by eliminating contact with Automattic, such as by disabling stats and Gravatar. I am using Total Choice Hosting. My blog is http://www.blogistan.co.uk/blog/ which is a single site (if you load, you won’t have this problem as you are not an admin).

I have noticed that others have reported slowness when logged in, but it’s not that it takes seconds rather than milliseconds to display the data, as others have reported – it’s that it doesn’t, at all.