There's only one snapshot in the zip (the instructions say to make 5 or so) so I can't tell if some of what it shows was just executing when the snapshot was made by chance, or if it was always executing.
(Correction: The instructions used to say to make 5 or so. That got lost when we split them out from another post. I'll add that back in. Our mistake!)
However, what I can tell from the single snapshot is that none of Opus's own threads are doing anything at all.
But something has created a large number of .Net threads (Opus doesn't use .Net at all, so we know they aren't ours) which are all doing various things, including network activity.
Avast Antivirus also looks like it's doing something, although it's hard to be sure if it's involved in the issue or not, since it's common for antivirus to get involved in any filesystem access.
I would try disabling all the shell extensions on your machine and then reboot, to see if that fixes the problem. If it does, re-enable a few at a time until it comes back, and you should be able to track down which one is causing it from there.
These are the non-Windows ones that the snapshot says are loaded into the process:
C:\Program Files (x86)\Microsoft Office\root\VFS\ProgramFilesCommonX64\Microsoft Shared\OFFICE16\MSOXEV.DLL
C:\Program Files (x86)\RedFox\AnyDVD\ADvdDiscHlp64.dll
C:\Program Files\AVAST Software\Avast\aswAMSI.dll
C:\Program Files\AVAST Software\Avast\aswhook.dll
C:\Program Files\Google\Drive\googledrivesync64.dll
C:\Program Files\Listary\ListaryHook64.dll
C:\Program Files\WindowGrid\WindowGrid64.dll
C:\ProgramData\MEGAsync\ShellExtX64.dll
You can use ShellExView (grab the 64-bit version) to disable them. After making changes, it's best to reboot.