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.