Interactive rendering slow at start

[Visual Impact]

Hi all,
Sometimes IR or a full render runs really slow for the first 30-60 seconds only using about 12% of the cpu, then it ramps up to 100%.
Any ideas why?

[maru]

That slow rendering time (the 30-60s you mentioned), is it the final "rendering" stage, or some pre-computation like "parsing geometry" or "calculating UHD Cache"?

[Visual Impact]

Final rendering stage, happens more often with IR.

[maru]

Can you create a minidump file when the CPU usage is low and post it here? (you should be able to do this if it's 30-60s)
If the minidump is big, you can compress it - it usually gets much much smaller.

Here is how to create minidumps:
https://coronarenderer.freshdesk.com/support/solutions/articles/5000524006
(see "2. Reporting errors or freezes if Autodesk Error Report window is not available")

[Visual Impact]

Ok, will do.