[rananna]

I was pulling my hair out trying to find the reason for calibre freezing every few seconds on windows 10. As part of the trounleshooting I discovered that shutting down the processes for Sticky Password fixed the problem!
Upon further investigation the "UI Automation" option was selected in Sticky Password and deselecting this fixed the issue.
From the Sticky password site:
"Sticky Password 7.0.5 incorporates support of UI Automation. Microsoft UI Automation is a technology that provides programmatic access to most UI elements on the desktop. It enables assistive technology products, such as screen readers, to provide information about the UI to end users and to manipulate the UI by means other than standard input.* UI Automation allows Sticky Password to interact with the 64-bit versions Internet Explorer 10 and 11 without requiring toolbar modifications, which means that no plugin will be required"

This is clearly interfering with calibre in some way.

Hope this helps someone, it sure was a subtle problem to track down!