Playlist edit command is slower then playlist add command with large playlists

Issue: Why does it take a long time to add song in Playlist(which is stored playlist not playing)
But not in Client Playlist( which is current playing) and how we can improve it?

Please find the same in detail in below:-

In Logitech Media server I understand there is two type of playlist.

1. Saved Playlist (which are not playing)
2. Current Playlist (which is currently playing)

So there are two types of command to add the songs to playlist.
1. Edit command to add a song to Saved playlist
Command is : "playlists edit cmd:add playlist_id:22 title:Song url:file://media/summerof69.mp3<LF>"
2. Add command to add a song into Current playlist
Command is : 1. <playerid> playlist add /media/summerof69.mp3
2. <playerid> playlist save <filename>

If we use edit command then some of the observation is mentioned in below email which is not at all reasonable :-
If playlist contain 1000 song: - to add a single song it will take 6 to 7 seconds.
If the playlist contains 2000 songs: - to add a single song it will take 10 to 12 seconds.
If the playlist contains 3000 songs: - to add a single song it will take 17 to 20 seconds.
If the playlist contains 4000 songs: - to add a single song it will take 27 to 30 seconds.

But if we add a song in the current playlist which has 5000 songs then it takes only 1 second which is fantastic.

Is there any other way to do reduce the time to add a song to saved playlist.

Please arrange some help at the earliest.

For information :- Test environment was
Songs are on NAS and NAS is mounted on PC
Network is Gigabit (Gbit)