DavidR
2
Closing the avastUI (including the statistics) and not leaving it open should return to more normal levels.
You should also know that there is a program update 9.0.2008, you can initiate a manual program update rather than wait your turn in the update cycle (to prevent overloading the update servers).
See image one with UI and Stats open, and image 2 just after both were closed.
The Statistics window (not so much the avastUI.exe as such) is pretty graphics intensive so will be using more RAM, but it should return to near normal levels when closed.