Very noticeable stutter / lag when adding children to scene tree.

[caliber06]

Godot version

4.0

System information

Windows 10, Forward+, i5-10400

Issue description

adding children to the scene tree results in a noticeable stutter in increase in frametime.

(all those spikes are when adding children)

Steps to reproduce

just add a child of a loaded instance using add_child()

Minimal reproduction project

N/A

[Calinou]

• Related to Godot 4.x is significantly slower than 3.5.1 in creating nodes #71182.

@caliber06 Please upload a minimal reproduction project to make this easier to troubleshoot.

Can you reproduce this when doing the same operation in 3.5.2?

[TokisanGames]

What is the child?

Is it a scene that has not been displayed on screen before this moment? (shader compilation)

Is it the same exact object being re-instanced on all of those spikes?

Does the object have any scripts attached?

Does the lag occur if you unattach and reattach the object from the scene tree? You should test on the same and subsequent frames. Use call_deferred for the latter.

just add a child of a loaded instance using add_child()

So it is not occuring when the object is instanced with .new() or load(). You already have an instance ready to go, eg created in _ready() and only when you add_child() it stutters? Or are you instancing the object and adding it to the tree all in one function? If so, test them independently.

Very noticeable stutter / lag when adding children to scene tree

What is stuttering? Is it just the blue ticks on the chart? These are insignificant, all about 1/60th of a second. Or does the whole engine seize? Does the mouse cursor move during the lag?

[caliber06]

What is the child?

Is it a scene that has not been displayed on screen before this moment? (shader compilation)

Is it the same exact object being re-instanced on all of those spikes?

Does the object have any scripts attached?

Does the lag occur if you unattach and reattach the object from the scene tree? You should test on the same and subsequent frames. Use call_deferred for the latter.

just add a child of a loaded instance using add_child()

So it is not occuring when the object is instanced with .new() or load(). You already have an instance ready to go, eg created in _ready() and only when you add_child() it stutters? Or are you instancing the object and adding it to the tree all in one function? If so, test them independently.

Very noticeable stutter / lag when adding children to scene tree

What is stuttering? Is it just the blue ticks on the chart? These are insignificant, all about 1/60th of a second. Or does the whole engine seize? Does the mouse cursor move during the lag?

the objects are being instanced and added at the same time. the packedscene that is being instanced has a script attached, which is a child class of a parent. I have tested instancing the object in _ready() and instancing it later on, same issue. The large AND small spikes on the graph are when adding children. The entire game freezes when adding objects to the scene tree like this. I won't be able to add a minimum-reproduction project until tomorrow.

[TokisanGames]

Does the instanced object have a shader material on it? Does placing a permanent instance of the object in the scene fix the problem when the new ones are instantiated?

[takhimi]

I notices the same problem also. Godot 3.5.2(in GDScript and C#) is more stable and faster on adding and queuefree() the children nodes.

I just tested by adding 1000-2000 AnimatedSprite2D with one animation to test it. Nothing fancy.

[Calinou]

If you can compile from source or use a precompiled debug build, try using a C++ profiler on a debug build to see what's taking the most time.

Edit: Please also test #75627 🙂

[takhimi]

If you can compile from source or use a precompiled debug build, try using a C++ profiler on a debug build to see what's taking the most time.

Edit: Please also test #75627 🙂

I should learn all this checkout , patch, branch etc2 from github first.