That was why I suggested using ShellExView to try disabling shell extensions back when the thread was new, or using Process Monitor if that didn't work. As you can see, within half an hour of seeing the Process Monitor log we were able to suggest particular extensions to disable, but you could also have found them by disabling everything and then turning things back on until the problem came back.
Hello, I also had a little delay after changing the folders. But after I disabled all the Autodesk shell extensions nothing was better. I noticed, that I had a lot of folder tabs above the listers, some invisible which pointed to network paths or the USB memory stick. After closing all the folder tabs everything was quick again.
I have Actual Windows Minimizer, but I don't encounter this error in no other software. I can not figure out which may be the cause, although I use many softwares that could interfere, such as Expandrive and Visual Subst.
I do also have a button in DO toolbar to merge two/more folders together.
We've found similar tools go wrong with Opus sometimes, usually because they make assumptions about the way threads are used in the program which aren't always correct. Sometimes they get updated to fix things once its drawn to their attention (but you'd need to verify the theory first, of course).
They may not be involved, but it would make sense to remove them temporarily to see if the problem goes away. If it doesn't, we can move on to other ideas.
The big issue in my case is when I try to rename and move files and folders. Although with a ssd and a i5 4 cores cpu, there are lags difficult to understand.
Following your advice, I tried to see if the problem persists if Windows Defender is turned off. So, I installed another antivirus software and voila: the slowness has disappeared!
I don't like the idea to stay unprotected, so I would recommend this way of solving the issue.