system
3
It’s not a bug, it’s a feature. Avast is trying to update as soon as possible and while continuing to stay in this process, it slows down the computer when you aren’t connected fast enough or can’t establish a connection for a while.
You might want to try looking for other AV programs since there are many who don’t block the start like Avast does when it’s waiting for the updates to finish, though I won’t name any, so take a look for yourself and try it out in a virtual machine, on a secondary computer or after an image backup + clean uninstall of Avast.