Folder operation in FileSystem dock cause all assets to be rescanned 3.3.2

[LATRio]

Godot version

3.3.2.stable.official

System information

Windows 10, 64 bit

Issue description

Return of issue #19991. Message "Scanning files. Please wait..." appears in FileSystem dock when creating a new folder or moving any folder and takes time to rescan all assets. Deleting folder doesn't show that message. Instead, deleted folder disappears after a delay. Amount of assets seems to affect length of delay.

Steps to reproduce

1. Create a new project and import assets (100+ textures for example)
   2.1 Create a new folder
   2.2 Move any folder
   2.3 Delete any folder

Minimal reproduction project

Download any assets online (like Kenney's) and import them into a new project.
Empty project can reproduce it too. But message will instantly appear and disappear

[Torguen]

Could you make the matter easier by adding a ready-made project?

[bmolyneaux]

Here's a reproduction project:
Scanning.zip

The "Scanning files. Please wait..." message shows up for about half a second for me.

The message is present much longer on my actual project which has thousands of assets.

[KoBeWi]

Seems like Godot keeps some filesystem cache internally. Even when you move the file to another directory and back, the cache will be different than at the beginning. It would be nice to have a smarter system that scans only when a file has changed (not moved) or was added.

[viksl]

You can also trigger this by right clicking to create new folder in the godot's FileSystem docker then after the pop up for the name shows up click somewhere else in your system outside godot (for example click on an opened browser window or something then click back straight to the popup with name, delete the placeholder, give it some name ("testname") and press ok, Scanning Files will get stuck at 0% forever, you can get it back working if you again click outside godot and then back it will immediately update.

[Hyrilorius]

It's still a big issue in 4.X

As my project starts to get bigger (a few hundreds, then thousands files), this is becoming a massive issue for me.

Creating an empty folder takes 10+ seconds and it really hurts the scalability on any project.
Any FileSystem operation, creating/moving a file/folder takes ages.

It looks like that issue was first tracked as a 4.X Priority issue, something to do for 4.0 and then removed from both the 4.X Priorities and 4.0 milestone, but without being put back in any 4.X milestone.

Any chance to put some love on enhancing the FileSystem speed for 4.3 or 4.X ?