Thank you very much.
By the way, I noticed that the problem only occurs when a project is open. As soon as the project is closed (CTRL+W), the menu item “File” opens without delay. So I guess it’s not the “projects” after all. (Had a hunch that Nuendo waits until a network drive wakes up, for example.)
Because of the “Atmos object thing”, I’m currently using version 12.0.40. But I’ve also noticed it with version 12.0.50.