I stumbled across something interesting as we are trying to improve performance and page load speed on one of our sites that use the Metabox AIO plugin. We have a custom post type with a field group, our field group is set to save to a custom table. We started implementing our field groups in custom tables as it is stated that custom tables perform better than the regular post meta table. However when inspecting the front end of our site to see if we have any slow queries running with a plugin called Query Monitor I have numerous slow queries being called by MetaBox\C\API::create() and altering tables. This happens on all pages site wide even admin pages and seems to be inconsistent between page loads - sometimes MetaBox\C\API::create() is attempting to alter multiple columns in a table and sometimes it is only trying to alter a few.
These queries sometimes account for a whole second in the page load speed.
As we strive forward in enhancing our site's performance, we were wondering if you could provide any insight on this and if it is all that necessary for these queries to be happening where tables/columns are being altered.