Render times increases drastically between Corona 9 & 12

[lollolo]

@romullus, interesting and nice to see that Corona got faster (unfortunately not for all it seems)

@habber, I'm using Win+C4D, most likely that's why I didn't notice a speed slowdown.

[jojorender]

I’m still on intel Macs. I keep more of an eye on r/sec instead of absolute render times, and r/sec stayed pretty consistent since V9 

The stats displayed in your VFB are definitely strange. Are you using team render or just a M1 max MBP?
I think 11M rays/ sec is too high for an M1 max, even if only clay mats are used.
I would run these tests again and override all mats with a simple clay material to make sure there is no weird corona bitmap shader hidden somewhere. Use simple glass or delete windows.

Did you ever benchmark your M1 max? What r/s are you getting in the benchmark?
The 24M r/sec in V12 is just wishful thinking - that would make your MBP the fastest Mac ever build and would even bring Steve back to life.

Do you know for sure the render times are actually that much slower (stopwatch?) and not just a stats issue?
Anyways, no idea what’s going on here but hope the devs can help with this.

[habber]

I normally don't pay attention to render times, because for me few percents slower or faster rendering is irrelevant, but out of interest i installed V9 and rendered random scene. Turns out V12 is significantly faster, which is not surprising. I noticed that the floor in V12 is rendered wrong though and that may indicate that there were some changes that affected complex materials between V9 and current version and that could possibly be the cause of slowdown in your case. Dramatic increase of rays/sample in your V12 render seems to support that guess. Other than that, it could be C4D or Mac thing as pointed by others.

Hey romullus,

I notice you are using windows. I think that this issue might be Mac / M1 related? Sometimes windows gets more programmers attention since more % are using windows.

As for speed difference: I would agree if it's "few percent" + or - but in my case it's double :(

Cheers,
habber

[habber]

The 24M r/sec in V12 is just wishful thinking

Hey Jojorender,

Fully agree - 24M is way too much for the m1max, and seeing the render times makes me think that this has to be a mistake. I've noticed this on all of my scenes. Depending on the scene, rays are usually between 2M (with tons of scatters and instances) vs 20M r/sec (simpler scenes), total render time with same passes still almost double though between V9 and V12.

Cheers,
habber

[Philw]

We’ve all suspected there’s something going on with the Apple Silicon implementation…would be good to get to the bottom of it. Maybe it’s the Apple Silicon port of the Embree raytracing libraries, the “clever” memory management, bitmap processing libraries or just something weird… who knows?

[prince_jr]

hi everybody

i‘m on mac, too (m2 ultra, 24c). with version 11.2/c4d 2024.2 i can‘t confirm double render times, because i can’t run v9 on v2024.2 anymore. but…
- i sometimes see strange numbers in the vfb (rays/s etc), too
- there’s slower render speed (felt)
 
a current interior scene needs ~15h to render (resolution of 4000x6000px). all materials are setup with cbitmap, mostly bump used and only a few displacements. plus illuminated by hdr and some basic lights outside the house.
is this normal?

i really hope the devs can figure it out with apple. i don‘t work as a visual artist nor make money of it, but it‘s no fun to render one image for 15h. i mean it‘s 2024 and not 10 years ago. ;o)

[habber]

i‘m on mac, too (m2 ultra, 24c)

Oh man that hurts to read ... m2 ultra 24 cores and taking 15 hrs per render is painful. that machine is a beast and so is its price. (im actually thinking of getting the same setup to complement macbook) anyhow, should be way faster than that. resolution is quite high but still...

what pass limit you use for noise limit? maybe you are even rendering too many passes? of course personal preference but maybe you are trying to reach noise limits that are just too hard to achieve within reasonable times? i'm usually more than fine with 5% for example. Actually end up adding some grain on purpose in post production. Gives it more realistic appearance and less "perfect CGI" style.

In any case, speeds are low on macs. they haven't been low before, they started getting lower after v9 which is the sad and not logic part to me. I'm now suffering on a daily basis. And since scatter brush is not out yet for v12 anyway i guess i will have to go back to v9 very soon since nobody of the devs has responded anything yet :(

Cheers,
habber

[prince_jr]

i‘m on mac, too (m2 ultra, 24c)

Oh man that hurts to read ... m2 ultra 24 cores and taking 15 hrs per render is painful. that machine is a beast and so is its price. (im actually thinking of getting the same setup to complement macbook) anyhow, should be way faster than that. resolution is quite high but still...

what pass limit you use for noise limit? maybe you are even rendering too many passes? of course personal preference but maybe you are trying to reach noise limits that are just too hard to achieve within reasonable times? i'm usually more than fine with 5% for example. Actually end up adding some grain on purpose in post production. Gives it more realistic appearance and less "perfect CGI" style.

In any case, speeds are low on macs. they haven't been low before, they started getting lower after v9 which is the sad and not logic part to me. I'm now suffering on a daily basis. And since scatter brush is not out yet for v12 anyway i guess i will have to go back to v9 very soon since nobody of the devs has responded anything yet :(

Cheers,
habber

@habber
sorry for not mentioning the noise limit. it‘s 3.0.
i know, maybe 4.0-5.0 would do the job and will of course provide lower render times. but in this case i primarily have a detailed stucco surface and want the fine details to be seen. i think noise limit 3.0 isn‘t very utopic to run with.

it would be so nice to get some information or at least some attention from the corona devs about that topic, which a lot of mac users does bother.

[habber]

sorry for not mentioning the noise limit. it‘s 3.0.

Got ya! Yes 3 is quite low (keep in mind noiselimit incrementes rendertimes exponentially) but regardless 15 hrs is too much.

Forgot to add 1 important point: I've never heard my fan on my m1max even while rendering heavy scenes on Corona 9. Those M chips are so good that I even forgot I had a fan since it never turned on. Now, even with simple scenes I can hear my fan kicking in on Corona 12 :(

Cheers,
Habber

[prince_jr]

sorry for not mentioning the noise limit. it‘s 3.0.

Got ya! Yes 3 is quite low (keep in mind noiselimit incrementes rendertimes exponentially) but regardless 15 hrs is too much.

Forgot to add 1 important point: I've never heard my fan on my m1max even while rendering heavy scenes on Corona 9. Those M chips are so good that I even forgot I had a fan since it never turned on. Now, even with simple scenes I can hear my fan kicking in on Corona 12 :(

Cheers,
Habber

@habber i did another render test. i managed to reduce the render time from 15h to 5.5h. but how...well, i was cheating a bit.

my approach:
positioning an omnidirectional light (sphere) in the room incl. compositing tag (everthing unchecked). the rendering of course is overexposed now. but in lightmix i turn off this light to get my desired exposure back. after 5 passes the rendering has 6.35% noise. in the render test with 15h the noise level was somewhere 15-20% at 5 passes. i don't know if this is the way to go, but it seems to help. does anyone have the same approach to get less noise and faster render times?

attached you will find two render test:
4000 x 6000px > 5h05min, noise level 3.0
3333 x 5000px > 3h30min, noise level 3.0
rays/s are normal. only rays/sample is high > 323.6
> specs: mac studio m2 ultra 24c, 192gb ram, 60c gpu, ssd 4tb – c4d2024.2 - corona renderer 11.2

any feedback from the corona team is welcome and appreciated.

[habber]

Very interesting workaround! It's wild that this trick would reduce render times by 2/3!

Also, wow your scene is so simple - beautiful but VERY simple - I had no idea. Not even using reflections or any form of special material.

Can't really understand how it would even take you this long, having such a strong machine. I can only guess displacement for the walls? (still shouldn't be as much) What do you use as setting for displacement size? I've realized this affects times a lot and the result being only slightly affected.

[prince_jr]

Very interesting workaround! It's wild that this trick would reduce render times by 2/3!

Also, wow your scene is so simple - beautiful but VERY simple - I had no idea. Not even using reflections or any form of special material.

Can't really understand how it would even take you this long, having such a strong machine. I can only guess displacement for the walls? (still shouldn't be as much) What do you use as setting for displacement size? I've realized this affects times a lot and the result being only slightly affected.

only the rock and the wooden piece have displacement. walls and floor are using bump.
render settings are untouched. displacement screen size (px)= 2 (see attachment)

i don't know how to tweak the scene and settings any further to reduce render time. maybe we have to accept that apple machines more and more suck when it comes to 3d-rendering.
but i have to say...i'm very happy with the mac studio. my main work is photography (commissioned) with medium format. and the mac studio does a marvelous job handeling the big raw files respectively filesize.