If your PC gets lag by using Avast then there must be virus in it. I face difficulty in uninstalling it from my computer and it last me up to 3 hours and after a lot of research, finally i found a working method. I am using Windows 10 OS.
When you block a person, they can no longer invite you to a private message or post to your profile wall. Replies and comments they make will be collapsed/hidden by default. Finally, you'll never receive email notifications about content they create or likes they designate for your content.
Note: if you proceed, you will no longer be following .