Render time taking to long

[husherson2]

I know that someone posted this issue a while ago and before posting, I've done a little bit of research to see if I could find the solution, but I couldn't.
So, here I am trying to solve my problem.

I have a simple scene, lit with Corona Sun and Sky (with a color correction just to adjust some things).
Simple materials as well.

The first time that I was trying to render the scene, to test some things, it took about 1 hour and a half (not that high resolution, around 2000x1500)
The only thing that I changed was a material on the wall (it's a interior scene) but the material was really simple (mapping the glossiness and bump only with very little tweaks).

I didn't change that much of the standard settings, but now when I try to render I receive estimated render times as high as 6 to 10 hours.

I don't know exactly what is wrong. Maybe I am running out of RAM, but this is strange because I guess it wouldn't take 1 hour at the first time.
I've attached some screenshots so you guys can maybe figure something out of them.

Free Ronaldinho

[TomG]

We'd need your hardware specs (CPU and RAM in particular), and an example render of the scene in question so we can see what you are rendering. Also, test your machine on the benchmark to make sure it's performing similarly to other machines with the same CPU (https://corona-renderer.com/benchmark/results).

[PROH]

Hi. First time I see someone setting the sun size to 50! That's HUGE!
Don't know if this impacts the render time, but out of curiosity: Does the render time change if you set the sun size to 1?

[husherson2]

Here are the results of my benchmark test:

Corona 1.3 Benchmark Finished
BTR Scene 16 passes
Intel(R) Core(TM) i5-3210M CPU @ 2.50GHz
Real CPU Frequency [GHz]: Undetected
Render Time: 0:15:00, Rays/sec: 539,827
RAM: 16GB

Hi. First time I see someone setting the sun size to 50! That's HUGE!
Don't know if this impacts the render time, but out of curiosity: Does the render time change if you set the sun size to 1?

Haven't tried that out yet, but will change and comeback with the results afterwards. Thanks for the tip

[TomG]

Render times will be quite long with that processor sorry to say - it's 8 years old, not top of the line back then, and a mobile processor. All those things mean that it is not a top performer; your benchmark time looks reasonable compared to others (https://corona-renderer.com/benchmark/results/cpu/i5-3210M) but it's around 14 times slower than my 8 year old processor (a dual xeon), which in itself is 3 to 5 times slower than more up to date processors. So you will have to anticipate longer render times with that hardware.

16 GB of RAM is also on the low side, you are not getting an out of memory warning from Corona when rendering this scene? That would make that scene even slower, as then it would be paging to disk too.

[husherson2]

Render times will be quite long with that processor sorry to say - it's 8 years old, not top of the line back then, and a mobile processor. All those things mean that it is not a top performer; your benchmark time looks reasonable compared to others (https://corona-renderer.com/benchmark/results/cpu/i5-3210M) but it's around 14 times slower than my 8 year old processor (a dual xeon), which in itself is 3 to 5 times slower than more up to date processors. So you will have to anticipate longer render times with that hardware.

16 GB of RAM is also on the low side, you are not getting an out of memory warning from Corona when rendering this scene? That would make that scene even slower, as then it would be paging to disk too.

No worries, I knew that my computer was old and with some lacks when it comes to performance, it was just strange to me that I could render initially with a render time of roughly 1 hour and after a few changes it goes to 6.
But yeah, I guess the problem is solved, pretty much is my faulty hardware.

Thanks for the help Tom!

[GeorgeK]

Render times will be quite long with that processor sorry to say - it's 8 years old, not top of the line back then, and a mobile processor. All those things mean that it is not a top performer; your benchmark time looks reasonable compared to others (https://corona-renderer.com/benchmark/results/cpu/i5-3210M) but it's around 14 times slower than my 8 year old processor (a dual xeon), which in itself is 3 to 5 times slower than more up to date processors. So you will have to anticipate longer render times with that hardware.

16 GB of RAM is also on the low side, you are not getting an out of memory warning from Corona when rendering this scene? That would make that scene even slower, as then it would be paging to disk too.

No worries, I knew that my computer was old and with some lacks when it comes to performance, it was just strange to me that I could render initially with a render time of roughly 1 hour and after a few changes it goes to 6.
But yeah, I guess the problem is solved, pretty much is my faulty hardware.

Thanks for the help Tom!

Do keep in mind when rendering with laptops there is a high possibility of thermal throttling, this will severely impact render times. I would suggest monitoring CPU temperatures and also clean-repaste the CPU if it's old and not recently maintained.

Lastly, you might want check with your manufacturer if there is a chipset update.

[TomG]

What were those "few changes" too btw? Definitely could be something like it took you over the memory limit of your machine, making things much much worse. Or could be it gained enough complexity to run for just a bit longer that caused overheating and so things slowed down dramatically after that, and so on. Might be a way to optimize around it to get back to that 1 hour :)

[husherson2]

Those changes were mostly materials. But the textures were all high resolution and they were more complex than the regular Corona 128 grey material.
Being aware of the overheating problem, I got 2 coolers today and they reduced drastically the overall temperature of my notebook. I did a render today and things went way smoother than the usual. Not that 1 hour, but a estimated time more acceptable.

I still must save some money to improve my hardware, but right now those few changes that I made as you suggested, did the job.
Thanks everyone!!

[TomG]

That's good to hear, and glad some things here helped!