Just looking at the resource monitor, svchost.exe is what is accessing the hard drive the most. Firefox, Edge, and Avast seem to be chewing up the RAM. My wife tends to open up 30 tabs with 20 animations per page, then log off with them open, so the browsers are no real surprise. Avast does seem to be continuously busy, though, probably as a result of all the live tile stuff. The CPCU seems to be kept busy first by 'system' followed by Avast and the browsers.
Might be time to switch off Avast and go with Win Defender or something a little more ready for Win10.