Corona 12 a lot slower on old scenes

[MarkusB.]

Hi everyone,

we just upgraded to corona 12 and did some test renders with projects from this year, all done with corona 11.
What we noticed is a huge increase in rendertimes, when rendering with corona12!

scene 1:
corona11: 27:21 min
corona12: 40:16 min

scene 2:
corona11: 6:25 min
corona12: 7:30 min

scene 3:
corona11: 4:40 min
corona12: 7:29 min

This basicly happens with every scene we open. All tests are done on the same PC (Threadripper 3970x), with same rendersettings.
Did anything changed from corona 11 to corona 12, so that old scenes need to be adjusted ?

Attachted are two screenshots. (had to blur the image, sorry)

Any help is greatly appriciated, because this increases are huge!

Thank you
Markus

[romullus]

Could you try to reset render setup and re-create it as faithfully as you can? It's possible that some settings got corrupted when loading a scene created in previous version and now it negatively impacts render speed. I didn't compared Corona 11 vs 12, but i did quick comparison to Corona 9 recently and the latest version was significantly faster.

[maru]

You are getting different rays/s values indeed. This may be a silly question, but are you sure it is not related to thermal throttling? There is currently a heatwave in a lot of countries.
If not, then we would be interested in checking your scenes: https://support.chaos.com/hc/en-us/requests/new

[MarkusB.]

Could you try to reset render setup and re-create it as faithfully as you can? It's possible that some settings got corrupted when loading a scene created in previous version and now it negatively impacts render speed. I didn't compared Corona 11 vs 12, but i did quick comparison to Corona 9 recently and the latest version was significantly faster.

Will give this a try tomorrow and report it.
To be sure, I will merge it all into a new blank scene.

[MarkusB.]

You are getting different rays/s values indeed. This may be a silly question, but are you sure it is not related to thermal throttling? There is currently a heatwave in a lot of countries.
If not, then we would be interested in checking your scenes: https://support.chaos.com/hc/en-us/requests/new

.
Workstation is watercooled and CPU temps never ever go above 65°C.

[MarkusB.]

Update:
Like suggested, I merged in the "old" corona 11 into a brandnew scene and setup corona12.
The rendering times went down indeed. We now have:

scene 1:
Corona11: 27:21 min
Corona12: 40:16 min
Corona12 (new file): 36:37 min

scene 2:
Corona11: 6:25 min
Corona12: 7:30 min
Corona12 (new file): 6:40 min

It renders faster now compared to just open the old file.
However, we are still a lot slower than corona 11.

Any more suggestions?

[Marijan]

I'm experiencing the same thing, especially on exterior scenes.
For the same amount of passes and noise level render times are quite different.
IR also seems slower in Corona 12.

Corona 11: 09:16 min
Corona 12: 13:56 min

AMD 7970x, Max 2024.2.3, Windows 11
I have reported this with one scene included (Id #268872).

[ProxyFuel]

Same here—I just made a post about it. There’s definitely something off with version 12. It’s noticeably slower when we test it across our machines. As a school, we have several computer labs with completely different setups, so it's not a specific hardware issue. Scenes that ran quickly in version 11 are now sluggish, even when merged into empty scenes. This seems like a software issue that needs to be addressed ASAP.

[maru]

(Last message continued here: https://forum.corona-renderer.com/index.php?topic=43436.0)