Access to Windows explorer is super slow

I have Windows 10 Pro working for a few months but yesterday something strange started to happen to explorer.

I don't know how to describe it so I will give some examples.

1. Windows File Explorer - when opening for the first time after system start i hangs for about one minute. After that it works fast with no problems. Doesn't matter if it's the Computer folder or any other. After closing and opening again the problem doesn't appear. Is happens again if I restart the explorer.exe process.


2. LibreOffice Writer - Save As and Open shows the dialog and hangs for 30 seconds (happens every time).


3. Notepad++ - well, this is one is really strange. Testing with open and save as dialogs. They always open but after confirming or canceling the main window hangs for 5 seconds. Also it doesn't always happen.


4. My own application, using Qt with native dialogs. Even stranger - sometimes it hangs when I open an open/save file dialog, sometimes it opens and seems to be responsive until I click something and sometimes it hangs for 30 seconds after dismissing the dialog.

Everything else is working fine e.g. browsing internet, loading in games and the issue seems to be bound to accessing files via explorer and open/save dialogs.

I've done some googling and run sfc /scannow. It has found corrupted opencl.dll and repaired it but that didn't fix the issue.
Disabling or even uninstalling AVP also does nothing.

Answer

Thanks to @BenN suggestion I've managed to solve the problem.

I've used Process Monitor to check what the explorer.exe hangs on. It comes out it was a faulty shell extension. I didn't install it recently, so I guess it became corrupted somehow. After uninstalling the problem is gone.

Edit2: It was DAEMON Tools 5.2.0 shell extension. Wouldn't blame it though, as it was working fine for several months.