Contrary to how Vim is usually used Emacs users tend to start only one Emacs instance and spawn multiple windows from that. This is because using a single Emac

Contrary to how Vim is usually used Emacs users tend to start only one Emacs instance and spawn multiple windows from that. This is because using a single Emacs session has certain advantages (completion, searching buffers, start up time (mostly a thing of the past now), etc.). However one disadvantage is Emacs not responding when it is busy with something else, like f.e. someone else mentioned Gnus retrieving mail. It doesn't happen often but it is annoying. I tended to use a separate Emacs instance for Gnus in the past.