Using the latest Nextcloud hub: My first ‘log in of the day’ can take 20 to 30 seconds. If I log out then in again it’s very fast. What can the admin change to cause the first log in to be quick?
The next time, you can use the web developer tools of your browser the next time you access Nextcloud for the first time. Then you can see which source takes so long to be loaded for the first time (after that, it is probably faster due to some of the caching mechanisms).