I have a site where the options_id field in the wp_options table has grown very, very large. A month and a half after the installation, the auto_increment value is now at over 10 million.
While there are a number of plugins installed (such as ACF and W3 Total Cache) they do not seem to be the cause. They have been installed on others sites together with the same theme framework without any issues.
I have a local dev environment of the affected site where all the plugins and theme updates are first tested. Its auto_increment value is only about 15,000 which I would expect given all the theme development on that install.
The site has also been very slow to load, at about 3 seconds per page if it wasn't cached by W3 Total Cache (with page caching enabled the load times are great). Given the slow load times and the high auto_increment value, there would seem to be some kind of connection between the two.
The options table itself only contains about a 1000 rows, which seems normal, so it is able to clean up after itself.
The site is part of a multisite network and each site in the network has at least an auto_increment value of 1 million or more.
Any other tables in the database haven't been affected, each of them shows a normal number of rows given the number of pages on each site.
Anyone have any ideas?