Godot4 using > 80% of the CPU when moving a directional light

[tavurth]

Godot version

Beta 1

System information

MacBook Pro (13-inch, 2019) 2.4 GHz Quad-Core Intel Core i5

Issue description

When starting a blank project in the new Godot4 beta I see >80% of the CPU being used at all times.

The godot editor also frequently becomes unresponsive, showing as Not responding in the task manager.

Steps to reproduce

1. Open a blank project in Godot beta 4 (1st beta)
2. Add a directional light
3. Move the directional light every frame

Minimal reproduction project

godot_directional_light.zip

extends DirectionalLight3D

func _process(delta):
	var amount = delta / 4
	self.rotation.y += amount

[tavurth]

[bruvzg]

Can't reproduce on M1 mac, It's about 1% on background and 6% idle on foreground.

[Calinou]

Related to #64708.

[tavurth]

Related to #64708.

Could be but in the above comment I have a screenshot showing the godot window unobstructed in the foreground 🤔

[tavurth]

Hmm I tried to build godot 4 to check this in a profiler but then I created a new project and the issue disappeared.

The original project I opened was actually the one referenced in this issue: #53969

So this issue still persists, but it seems now it has become a CPU bound operation.

[tavurth]

godot_directional_light.zip

This is the project which causes the CPU drop @bruvzg

[tavurth]

@Calinou is this expecting too much from the renderer?

We are moving the directional light every frame after all 🤔

[Calinou]

We are moving the directional light every frame after all thinking

Yes, this should be avoided when possible. AAA games that feature day/night cycles will generally move the light only 20 times per cycle or so, snapping between increments every so often (with a small period of continuous transition that only lasts a few seconds).

Changing the sky update mode to Real-Time in the Environment resource should help decrease CPU/GPU usage a bit when updating the sky, but moving the light continuously all the time should still be avoided.

[bruvzg]

godot_directional_light.zip

This is the project which causes the CPU drop

It's the same, 7-8% on M1 mac, probably it's an issue with a older Intel GPUs.

[clayjohn]

@tavurth How is your performance when using the realtime update mode? When updating every single frame the realtime update mode is likely a better option than then automatic mode. In either case though, updating the sky every frame on a low powered integrated GPU is probably going to consume a large portion of your frame budget. I recommend setting the DirectionaLight3D's sky_mode to LIGHT_ONLY so that the sky is not updated every frame along with the sun.

[tavurth]

Ok this is weird but I now have around 18% CPU usage in the same scene.

The only thing I've changed is renaming the folder.

Could it be that Godot4 is somehow re-using the cached shaders from the previous Godot3 version?

Renaming the folder back does not bring back the CPU usage however.

I will close this for now as sadly non-reproducible 🤷