Hi,
In reply to upper questions:
1) I have used corona 3, corona 4 hotfix 1 and corona 5 from 27 september daily build. Corona 3 lags a lot but corona 4 and corona 5 crashes instantly as I run IR by either turning off denoiser from performance tab or limiting core usage in IR in system.
2) I have tested it again and again on multiple 3dsmax version starting from 3dsmax 2017, 3dsmax 2018, 3dsmax 2019 and 2 hr ago, I just tried 3dsmax 2020. and problem is same throughout.
3) Here is a video I made (
https://www.dropbox.com/s/3xdnfopmk2qptwe/corona%20bug.mp4?dl=0)
4) If you see the video above, the lag is that much that I can not move windows and even stop IR. Also, you can see in task manager that ram is about 40% fill and both graphics card are normal at 1 to 2%. Only cpu is being utilized. Also to mention, the process also shows that no other application is utilization cpu as much as 3dsmax while on IR.
5) I have ran some bechmark softwares of corona, vray and indigo. All 3 seems to work flawless without any lag. I have put the system on stress test too and monitored the temps of cpu and motherboard. Everything seems normal and good.
6) All other application and 3dsmax alone work nicely and smooth when not on IR or rendering mode using corona. As soon as I start rendering, system almost becomes unusable.
7) these is like 56 gb of ram.
8) As you can see in the video, the scene is just 3 objects and corona environment white color. thats it. Nothing fancy.
9) I do not have avast, I use windows defender for now lol :D
10) All the gpu drivers and windows 10 are uptodate.