@alex-trefilov
The problem is probably for files in network shares.
Notepad++ tries to open a file which its path refers to a network share, Windows tries to reconnect with the shared folder and if the shared server is not accessible, the networking timeout is long until the file open fails. Since Notepad++ is single threaded timeouts for multiple files (mainly on different shares) can accumulate into a very long delay.
Notepad++ does not know if a path refers to a local file or to a network share so it can’t really do anything about it.
The only solution I am aware of is to give up the “Remember current session” and let Notepad++ open empty every time.