While HIF files certainly load slower for me than something like a JPEG, 10-20 minutes to load the content of a folder sounds like there are other things going on.
For a problem like this, I suggest contacting our support folks at:
By email: support@camerabits.com
By phone: +1 503.547.2888
Hours: Mon-Fri, 9:00am-5:00pm [PST/PDT]
I'd probably recommend calling, for this issue, but if you'd like to troubleshoot by email, please send us your log file, which you can find by going to Help -> Reveal Support Data and clicking 'Yes' in the window that appears.