Hi,
I’m using the Avast Passwords module (given with Avast Pro edition) with the extension associated with my Firefox browser 49.0.2 (x64) under Windows 10 Pro 64 bits. This extension works correctly with most sites but blocks the browser in some cases. For example, browsing a PhpMyAdmin site is simply impossible. navigation becomes extremely slow and every action on the keyboard or mouse requires several seconds of reactivity.
I did several tests by restarting Firefox in safe mode (all extensions disabled) and then reactivating the extensions one by one. Only the one related to Avast Passwords generates these performance issues. I did not test with another web browser (ie : Chrome).
Regards.