When the user connects to a remote display when nobody is logged-in, the GDM login screen is presented to the user. Everything works fine until the user types the password to login and start a new GNOME desktop.

Since then, it takes a long time (up to 30 seconds) to the new desktop to be displayed by NoMachine client.  During such transition, the client shows the login screen frozen or sometimes flickering.

This issue doesn't look specific of a certain GNU/Linux distribution, but it is quite evident with openSUSE Leap 15.