Houdini 21 Vulkan viewport slow with instancing?

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Is any one else experiencing pretty bad viewport performance when instancing? I have a scene with only a few thousand instances, and the entirety of houdini slows to a crawl when switched to the vulkan viewport. Switching to karma makes everything go back to normal, so i think it is a vulkan thing? I don't remember it being this bad before but i may be wrong. Am i missing something maybe?




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This doesn't solve any of your issues but you can try comparing it to OpenGL performance by switching it in the preferences [www.sidefx.com].

It will help to at least narrow things down to Vulkan if things are fast in OpenGL.
Edited by beatreichenbach - Sept. 9, 2025 23:45:20
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This doesn't solve any of your issues but you can try comparing it to OpenGL performance by switching it in the preferences [www.sidefx.com].

It will help to at least narrow things down to Vulkan if things are fast in OpenGL.

Thank you, great idea. It looks like the performance is better with OpenGL, Around 30 fps, so still not great but more than fine. It does look worse though, so i guess there is that to account for the performance difference. All in all i'll stay with vulkan, it got a bit better somehow yesterday, around 14 fps now, don't really know why but i won't complain.
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Vulkan renders with a lot more bells and whistles than OpenGL (and if you're going to compare them, make sure to set OpenGL to "high quality" mode). There are probably some quality-related toggles you can turn off to improve viewport performance with Vulkan, but unfortunately I don't know what those would be. Try switching to a headlight-only working light, make sure stuff like shadows and AO are turned off (RMB on the "disable materials" button on the right of the viewport). I'm sure there are other settings that would help...
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