[ul][li]Have you got a real-time anti-virus scanner? Tried disabling it?
Depending on which columns you have disabled, Opus tends to open and inspect files more than Explorer, which may be triggering your anti-virus scanner to inspect all those files (and it may have a long queue of files to inspect due to just booting). Just an idea, though.
(FWIW, I use anti-virus without this problem but some it may depend on the A/V program and/or settings and/or Opus setup. Or it could be something entirely unrelated.)
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[li]Checked for any drives mapped to network devices that are unreachable?
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[li]Tried turning off all Opus columns (other than Name and Size) and viewer plugins (especially the Movie plugin)?
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[li]Here's a list of other things to try:
General slowdown or instability investigation steps
I just added an extra suggestion near the top of that list, which is to clear Opus's File Collections (in case checking their contents in the background during startup is contributing to the slowdown; although it's done on a low-priority background thread and wouldn't normally be noticeable).[/li][/ul]