Threaded function is unusual slow under some conditions

[IceflowRE]

Tested versions

v4.2.1.stable.official [b09f793]

System information

Godot v4.2.1.stable - Windows 10.0.22631 - Vulkan (Forward+) - dedicated NVIDIA GeForce GTX 1080 Ti (NVIDIA; 31.0.15.4633) - AMD Ryzen 9 7900X 12-Core Processor (24 Threads)

Issue description

I tried to use ImageTexture.create_from_image in a thread and was surprised that the performance is around 10x slower than when being used in the main thread.

If the line self._load_progress = float(idx) / 2000.0 * 100.0 is removed or commented out, the threaded performance drops to 30x slower.

Might be related to #36793.

Steps to reproduce

Just run the attached project.
Results are printed to log.

Minimal reproduction project (MRP)

MTSlow.zip

[smix8]

Creating new textures or changing and receiving image data stalls the RenderingServer as data need to be received from or updated on the GPU. You are basically pulling the handbrake on the rendering loop at that point that needs to lock when you query the server api like that randomly from a thread so bad performance is expected.

[IceflowRE]

What is the alternative? If there is any.

[AThousandShips]

Try enabling threaded rendering, though it has its drawbacks and instabilities, otherwise don't do it on a thread but on the main thread on request, just generate the data on the thread, you're not going to be able to pass the data to the rendering device at the same time anyway due to communication channels AFAIK, so set up the data and request it to be updated on the main thread, as a producer/consumer setup

[IceflowRE]

Try enabling threaded rendering, though it has its drawbacks and instabilities

This wont be possible, it is used in a plugin.

otherwise don't do it on a thread but on the main thread on request, just generate the data on the thread, you're not going to be able to pass the data to the rendering device at the same time anyway due to communication channels AFAIK, so set up the data and request it to be updated on the main thread, as a producer/consumer setup

The consumer/producer could work, but would increase the complexity a lot, especially when loading 10k or 20k of textures.
As i should not load it in one frame.