LSP extremely slow when certain scene has instance of another scene

[rcorre]

Tested versions

Reproducible in: 4.3.1.rc.custom_build.90f21a35c

System information

Godot v4.3.1.rc (90f21a3) - Arch Linux #1 SMP PREEMPT_DYNAMIC Sat, 08 Feb 2025 18:54:55 +0000 - Wayland - Vulkan (Forward+) - dedicated NVIDIA GeForce RTX 3080 (nvidia; 570.86.16) - AMD Ryzen 5 5600X 6-Core Processor (12 Threads)

Issue description

When editing Player.gd in my project, the LSP is extremely slow. It takes several seconds for diagnostics or completions to update. If I remove the ThirdPersonModel node from Player.tscn, the LSP performance drastically improves. I'm using the LSP via the helix editor.

Before:

After:

Steps to reproduce

1. Open Player.gd in an external editor using the LSP.
2. In _ready, try typing rollback_
3. Wait for completions to appear, it takes several seconds.
4. Delete ThirdPersonModel from Player.tscn
5. Note that the LSP is now much faster

Minimal reproduction project (MRP)

I spent a while trying to minimize my project. It could probably be taken further, but this is relatively minimal.

example.zip

[ghost]

Cannot reproduce when using VSCode. The LSP responds instantly, even without deleting ThirdPersonModel.

Godot v4.3.stable
Manjaro Linux #1 SMP PREEMPT_RT Thu Jan  9 22:11:24 UTC 2025
X11 - Vulkan (Forward+)
dedicated NVIDIA GeForce GTX 1050 Ti (nvidia; 550.144.03) - AMD Ryzen 7 2700 Eight-Core Processor (16 Threads)

[HolonProduction]

Might be a duplicate of #100934

Could you check, how the behavior changes, depending on if the scene is open in the Godot editor.

[rcorre]

Wow, I spent a bunch of time trying to get an MRP last night, and was confident I could still repro. Now I can't repro, even on my original, non-minimized project. If it comes up again, I'll try closing the scene and running with #101091.

[rcorre]

Ok, I can repro again, and closing the scene does not help. However, #101091 does seem to resolve the issue!
I think this can be closed as a dupe of #100934. Thanks!