EEVEE Next: very low performance with hair particles #114752

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opened 2023-11-12 08:19:17 +01:00 by Sun Kim · 4 comments

Sun Kim commented

2023-11-12 08:19:17 +01:00

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System Information
Operating system: Windows-10-10.0.19045-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 2060 SUPER/PCIe/SSE2 NVIDIA Corporation 4.6.0 NVIDIA 545.84

Blender Version
Broken: version: 4.1.0 Alpha, branch: main, commit date: 2023-11-10 13:41, hash: cb5f650a5aa1
Worked: n/a

Short description of error
EEVEE Next shows very low performance with hair particles, leads to very unresponsive viewport experience in comparison to the legacy EEVEE.

Test file: eevee_hair_particles_performance.blend

It has 20 parent hair particles, 10 strand steps, 200 children particles.

In the legacy EEVEE viewport plays in more than 60fps, while in EEVEE Next viewport plays in around 2.5fps.

For a real-life example you can check out the 2.81 splash screen "The Junk Shop" file, in which the character uses hair particle with similar settings.

**System Information** Operating system: Windows-10-10.0.19045-SP0 64 Bits Graphics card: NVIDIA GeForce RTX 2060 SUPER/PCIe/SSE2 NVIDIA Corporation 4.6.0 NVIDIA 545.84 **Blender Version** Broken: version: 4.1.0 Alpha, branch: main, commit date: 2023-11-10 13:41, hash: `cb5f650a5aa1` Worked: n/a **Short description of error** EEVEE Next shows very low performance with hair particles, leads to very unresponsive viewport experience in comparison to the legacy EEVEE. Test file: [eevee_hair_particles_performance.blend](/attachments/1edb7b00-293d-4c62-9c77-77b565e0f574) It has 20 parent hair particles, 10 strand steps, 200 children particles. In the legacy EEVEE viewport plays in more than 60fps, while in EEVEE Next viewport plays in around 2.5fps. For a real-life example you can check out the 2.81 splash screen "The Junk Shop" file, in which the character uses hair particle with similar settings.

eevee_hair_particles_performance.blend

988 KiB

Sun Kim added the

labels 2023-11-12 08:19:18 +01:00

Richard Antalik added

EEVEE & Viewport

and removed

labels 2023-11-12 20:39:58 +01:00

Sun Kim commented

2023-11-13 11:49:48 +01:00

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Contributor

@iss Hi, thanks for confirming the report. Can you add the EEVEE-specific label too? So people come from this thread can see this listed as known issue.

@iss Hi, thanks for confirming the report. Can you add the EEVEE-specific label too? So people come from [this thread](https://devtalk.blender.org/t/blender-4-1-eevee-next-feedback/31813) can see this listed as [known issue](https://projects.blender.org/blender/blender/issues?state=open&labels=1138).

Richard Antalik added the

label 2023-11-13 23:28:43 +01:00

Miguel Pozo commented

2023-11-15 20:20:49 +01:00

Member

There are few things going here, the main performance hit comes from shadow rendering.
This is in part because shadows in EEVEE Next are slower/higher-quality, and still missing some optimizations.

But it's worth noting that you have the hair Strand Steps set to 10. That's 1024 vertex per hair strand (4096000 verts in total)!

I'm leaving this open since there are issues that still need to be solved (although they're not really specific to hair),
but keep in mind that setting the Strand Steps to a more reasonable value will give you much better performance.

There are few things going here, the main performance hit comes from shadow rendering. This is in part because shadows in EEVEE Next are slower/higher-quality, and still missing some optimizations. But it's worth noting that you have the hair Strand Steps set to 10. That's 1024 vertex per hair strand (4096000 verts in total)! I'm leaving this open since there are issues that still need to be solved (although they're not really specific to hair), but keep in mind that setting the Strand Steps to a more reasonable value will give you much better performance.

Sun Kim commented

2023-11-16 10:34:01 +01:00

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Contributor

@pragma37 Hey, thanks for the explanation. (Not only here but in other reports as well!)

I was wondering why the 2.81 splash screen file was lagging so much with EEVEE Next, and found out the issue with hair. So I made a simple file to replicate that for the report.

For some reason I personally don't see disabling shadows improving performance.

Comparison of render times:

EEVEE Next (with shadows, without SSGI): 24.97s
EEVEE Next (without shadows and SSGI): 25.2s
EEVEE legacy (without shadows): 0.63s

I get that the hair is really excessive (I also converted it to hair curves and performance seems to be in line with particle one) but still hope the performance won't regress that much in the end!

@pragma37 Hey, thanks for the explanation. (Not only here but in other reports as well!) I was wondering why the 2.81 splash screen file was lagging so much with EEVEE Next, and found out the issue with hair. So I made a simple file to replicate that for the report. For some reason I personally don't see disabling shadows improving performance. Comparison of render times: - EEVEE Next (with shadows, without SSGI): 24.97s - EEVEE Next (without shadows and SSGI): 25.2s - EEVEE legacy (without shadows): 0.63s I get that the hair is really excessive (I also converted it to hair curves and performance seems to be in line with particle one) but still hope the performance won't regress that much in the end!

Miguel Pozo commented

2023-11-16 16:53:43 +01:00

Member

Right now shadows are still computed even when disabled, that's why there's no performance difference.
And they are being re-rendered more than once per frame (which shouldn't be the case for the actual release).

Still, we may need to tweak the way we render hair/curves, because even after the mentioned issues are solved, the way the new shadows are rendered doesn't play very nicely with it.

Also, thank you too for all your reports, they're always very high quality. 🙂

Right now shadows are still computed even when disabled, that's why there's no performance difference. And they are being re-rendered more than once per frame (which shouldn't be the case for the actual release). Still, we may need to tweak the way we render hair/curves, because even after the mentioned issues are solved, the way the new shadows are rendered doesn't play very nicely with it. Also, thank you too for all your reports, they're always very high quality. 🙂

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