I'm using the latest 6.17 and it freezes constantly for up to a minute. Of the dozens of apps I have on my computer this is the only one struggling with Win11.
I don't have any additional anti-virus software running besides the stock Windows Defender. I've seen this post,
https://manual.calibre-ebook.com/faq...s-occasionally
but unfortunately I haven't been able to pin down how to fix this critical issue.