Clicking on res:// folder is very slow

[KoBeWi]

Godot version

0056acf

System information

Windows 10 x64

Issue description

When you click res:// folder in filesystem dock, it hangs the editor for a few seconds:

(this is release build)

Steps to reproduce

1. Click res://
2. 🥶

Minimal reproduction project

No response

[Mickeon]

It may be a regression of Tree itself, but I can't figure this one out. There's a lot of slow calls happening specifically when selecting the root TreeItem, and it may only be most noticeable on the FileSystem because there's a lot of... TreeItem children.

[KoBeWi]

Doesn't seem to be happening anymore.

[KoBeWi]

No it's still happening, but it's not obvious. You need to click another folder first and then right-click the res://. Subsequent clicks don't cause freeze.

[radlotus]

I noticed that in Godot 4 selecting a TreeItem causes a huge spike in "Physics Time" in the Profiler unlike in Godot 3. On my low-end hardware selecting an item within 10 000 items in Godot 4 causes a ~700ms delay while in Godot 3 it's instantaneous.
The Tree node is generally significantly slower in Godot 4 than in Godot 3.

[Maran23]

This also happens with the scene tree editor, not even a big one.
I agree to @radlotus, the tree is significantly slower and feels more sluggish on Godot 4.
So the task would be to find and improve the performance bottlenecks of Tree/TreeItem in general.

[Zireael07]

I've been feeling that the remote tree is more sluggish in 4 than in 3.x, and kept wondering why. This looks like it might be the culprit...

[KoBeWi]

Regression from #41242
Clicking res:// will recursively scan every file in the project.