While not technically proven, it seems like pages load considerably faster when logged out than while logged in. We should determine whether CentralAuth is to blame and check how significant the difference is between an account with 3 attached wikis and one with around 1000 wikis.
If the difference in load time is consistently considerably different we should consider (after an RfF) disabling create on view and making it a opt-in preference.
Tested today on testwiki (this should be attempted another day and another time to see if there's any difference). Results quite inconsistent.
Logged into my own account:
Special:WikiForum- 600ms
Special:RecentChanges - 1040ms
MediaWiki:Common.js - 294ms
Sandbox - 364ms
Logged into test account:
Special:WikiForum - 312ms
Special:RecentChanges - 597ms
MediaWiki:Common.js - 731ms
Sandbox - 818ms
With the introduction of WebAuthn in T10700, in my opinion disabling create on view is not really an option anymore. Doing that would mean that users of WebAuthn would be unable to create accounts at wikis they haven't visited before, as these users depend on CentralAuth's create on view to create accounts on these wikis.
wgCentralAuthCreateOnView has been removed in 1.40 as a config but wasn't used in any other code before 1.40.
PR to remove the setting since it has been removed in 1.40 https://github.com/miraheze/mw-config/pull/5355