Just installed Avast.
It does have a silent/gaming mode, it also try's to install a virtual instance mode service which you can tell it not to if you choose a custom install and drill down in the options to disable it. If you goofed and did anyway, run an uninstall then choose to remove components. You will find the virtual service and it will be uninstalled. It's supposed to be some kind of virtual unconnected sandbox to hold suspicious things in. Might be what was quarantining programs and games in the background.
If you watch online movies, every time a new file segment is streamed, avast grabs it for a few moments. If you do searches for information about removing avast services and try to read articles that are not at Avast's home page. Avast protects you from those pages.....sneaky.