Sorry for taking so long to reply. We've been working through a long list for the new version.
Some things to try:
[ul][li]Assuming the folder tree is open, do things go faster if you close it?
If that does speed things up, try turning off the Preferences / Folder Tree / Contents: ZIP files and other archives option and see if it is a factor.
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[li]If you're using any cloud storage software in your downloads folders, a quick thing to try is setting Preferences / Folders / Folder Display: Show generic icons for: All folders.
You would not want to leave it set like that, but it lets you test whether a cloud storage tool is causing delays with icon lookup. (We made some changes recently to reduce the impact of that, but it could still cause unexpected delays depending on how the cloud storage tool works.)
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[li]Crash, exit or high CPU when viewing certain directories has instructions on how to find out if the problem is being caused by a 3rd party shell extension. They're often involved in things which only affect certain folders.
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[li]You can create a Process Monitor log which records what Opus and other software is doing on the machine during the delay. Make sure the log includes Registry and File System events (using the icons on the right of Process Monitor's main toolbar).
If you File>Save the log from within Process Monitor, using PML format, and zip the result, you can email that to leo@gpsoft.com.au and I'll see what it reveals.[/li][/ul]