It’s sort of annoying. Users cannot be auto logged into the forums (even if the browser remembers your password) and if you forget to log in before replying to a post, it takes you all the way back to the main forum page and you then have to browse to the sub-forum and hope you can find the post.
When logging in please make sure to chose to remember the login forever. By default it will only log you in for an hour. You will have to log in using the login page and not the login on the top of the page.
When viewing a post then decide to login to reply, bookmark the post for convenience. :-La