Slow, browser processes do not unload on exit

Just installed Avast Secure Browser version 70.0. Ran fine at first. After running for about 12 hours, all processes on computer slowed to a crawl ( about 10% normal). After exiting browser, about 12 hives remain active in RAM. If I shut one down via Task Manager, it immediately spawns another! Running AMD Athlon II, 8 G RAM, Win 7 64X.

A friend suggests Control Panel>Internet Options OR browser settings may include option to force complete unload at exit? Tried Browser>Settings>Advanced>“Continue running background apps when Avast Secure Browser is closed”: set to OFF. Exited browser, still have 12 processes running! This is unacceptable behaviour.

Further — logged off, logged on, Avast Browser loaded in background even though Settings Load at Startup is OFF. Uninstall time.