I had a problem with speed in my administration area and the WPEngine technician pointed out a very long query instigated by the Types plugin, image attached. He also said the following:
What I did find was that, the screenshot I posted a bit ago is related to the Types plugin you have. I recommend getting with that plugin developer to see if any queries can be optimized. The plugin was trying to do:
SELECT * FROM wp_postmeta WHERE post_id IN(ID)
Replace ID with the number seen from screenshot (which is quite a few)
Hi Nigel. I was navigating around the admin area, mainly between pages and it was incredibly slow. The technician spotted one plugin that I have disabled (not one of yours) that was continuously hitting the database even when it wasn't being utilised, and then identified this issue. I can give you access if you want to look