This plugin is very bad written. It does scan every webpage when there is a form field. You can not disable this, neither you can exclude pages in the extension to be scanned. At moments it fills in form fields without authorisation. It is a violation of privacy and it does slow down firefox, especially when you are in such thing like an admin section of a website. After reports to Lastpass, they suggest to disable the plugin and use only the password manager through their website, but after 2 years doing so, they did not solve the issue at all. I suspect they like to monitor our visits to websites to metric our behavior. Do not use it.