I'm not entirely sure but I guess It's a normal thing because while being logged in, there are some checking that you really need to do and that could require a database connection which will make the loading a little bit slower.
An example to give is the trust profile, If you are logged out then you don't really see it on the trust of users, while checking a section too, you have to check If you have already seen the threads or not, If you didn't they are in bold otherwise they are normal and that check is not done while being logged out.
Yes, but I tried logged in with a new account which was fast. Which means the trust profile, subscribed threads or read/unread tracking could be the issue.