1 too many scans. 
2 schedule the screensaver scan when you're not using the computer.
Should work fine unless you never sleep. 
But when I'm not using the computer, it is switched off. I don't like wasting electricity by leaving computers on doing nothing - have you seen the cost of energy bills in the UK?

That's why the scan is scheduled for when I know I will be using the computer. It has no discernible impact on performance running in the background doing it's thing. The only issue I have is that the silly UI pops up now when it's done.
It boils down to the fact I paid £39.99 for a piece of software because that piece of software was doing what I wanted it to do. I could have run a Quick Scan every hour, if I wanted. Now it's doing something that's annoying to me and is, in my view, largely unnecessary. The answer shouldn't be for me to modify my behaviour to cater to the change in the software's behaviour because when I licenced it, it wasn't behaving in this manner. The answer should be for Avast to change the behaviour of the software back to how it originally was or if there is some advantage to what is doing now to make that optional.
Because, to be honest, even if others think that running a Quick Scan once a day is excessive, there's plenty of other options on the market that will let me do just that without popping up it's UI every time it's done. One of the reasons I perform a Quick Scan every day, and the primary reason I switched to Avast, is because another AV provider which had resident, real-time scanning and all that let nasties get onto my system four times in two weeks. I'd rather err on the side of caution than spend hours fixing such a mess.