Well don't know if i am suffering the same thing, i had avast for free for few years, but back end of last year took out premier cover, my computer came to a stand still for around 4 weeks, couldn't run two programs at once, and when you did it took ten minutes to load, getting on to the internet was a nightmare, i had a friend take a look at my computer thinking i had a virus or worse and even he couldn't work it out, then one day it worked fine, so thought avast must have been running a clean up etc in the background.
Well yesterday it installed new software or updated was told by my friend, and its gone back to running, or should that be walking speed, just can't do anything, its a right pain in the !