In that .PML file that I attached, I could see that it accesses the SMB directory, even though it was never pinned to the folder tree):
Just the fact that the tab was left open made this request.
I hopefully made the folder tree to always be collapsed on start, and I'll see for the next days if it makes any difference. Such a little thing, but so annoying when it slows me by these few seconds everyday 
The Folder Tree panel needs to be closed entirely. (Not still there but with all branches collapsed; that wouldn't be enough to test if the tree is involved.)
Edit: Can you send us a Process Monitor log (.PML format) capturing the event shown in the screenshot? We can get a stack trace from there to see why they're being called.
Oh, I sent it to you on private message on Dec 21 2023. I'll send again to make sure.
Looks like it's getting the name and icon of the drive which is waking it up.
Try turning off:
And make sure this is set to False (which is the default):
Thank you for your time.
I unchecked the "Display localized folder names", and "custom_network_folder_icons" was already false.
Unfortunately, there's no difference. The HDD on the external NAS is still waking up when opening Opus for the first time, after some inactivity.
I learnt to live with this problem and close remote tabs before closing the Opus, this is why my replies are slower. I believe the problem might only be reproducible on certain configurations, e.g. low RAM NAS device where remote folder files list is not always in cache.
