If you are satisfied that you really never want to see any new groups,
you can set gnus-check-new-newsgroups to nil. This will
also save you some time at startup. Even if this variable is
nil, you can always subscribe to the new groups just by pressing
U in the group buffer (see Group Maintenance). This variable
is ask-server by default. If you set this variable to
always, then Gnus will query the back ends for new groups even
when you do the g command (see Scanning New Messages).