Hi @randler
All plugins are loaded on each page load. A well written plugin will look at the current screen and load it’s ‘includes’ if needed, however, a not so well written plugin will always load all it’s ‘includes’.
Please disable all plugins to confirm the issue is related to plugins load.
Please also change your theme to the default twentythirteen. This will reveal if the issue comes from code in your theme.
Please also contact your host and ask them if they can see any stand out issues on the page load in question.
And please setup a local instal of the website for testing. This will remove many server variables and allow you to debug and find answers quickly.
Thanks
E
