CPU Usage Decreasing while pre-pass

[aokcub]

Though there are some topics relating to the CPU usage but this may be another one...

With v4.5.42.f, the CPU usage gradually decreases while pre-pass and finally goes to 20-30% (though pre-pass progress is <10%, see the first screen shot)
I don't experience this with v4.4.67. (see the second screen shot)


Does anyone have any idea on this? I'll put tgd for investigation.
cpuusage_r1.tgd

Configuration
Ryzen 3950X
DDR4-2666 128GB RAM
Windows 10 Pro x64 (clean-installed prior to testing)

Troubleshooting
No difference between standard camera and spherical camera (but a point of decreasing is slightly late when standard camera is used)
The issue occurs with the scene that doesn't contain v3 cloud.
The issue is not solved unchecking bucket size auto reduction.

[WAS]

I haven't noticed the pre-pass being slow but PT renders are really bad when they do close terrain. Takes forever. Even without shadows. I'll still have 12 buckets going but they will be chugging for 10+ hours compared to the rest of the whole image done in a couple

[Matt]

I'm seeing reduced CPU usage on my machine too, but not as much as in your graph. I will look into it.

[aokcub]

Thank you, Matt.

I shared the scene file with A4size (3960X) and he observed same behavior, but with another scene, his machine runs normally.
I wonder what happened.

[Matt]

The culprit is "Better cache radius" in the atmosphere. It's automatically enabled when you load a scene into v4.5.38+, but you can turn it off and the speed should return to normal. I'll figure out why it's causing this slowdown and try to fix it for future builds.

[aokcub]

Yes, now it's working well.

Thank you for the quick support!