I suggest you try some other antivirus if repairing avast didnt make any diff.
Avast Smartscans are supposed to be very quick 5-10 min smartscan), but it isnt a comprehensive scan which I need to do next anyway and god knows how much time that's gonna take if the smartscan itself is so slow =/ of page faults eset was giving me + the high cpu usage for eset that i noticed yesterday (eset's good too, but i wanted to try avast as a 'tech-savvy' friend recommended avast and i wanted a 2nd av scan result). I switched from ESET to Avast because of the ridiculously high no. Esetnod32 had completed the scan & reported no viruses earlier b4 i uninstalled it + i also ran the basic win10 memtest and HDD scan diagnostic tests to try to rule out any hardware problems for me (everything came out fine but I have my doubts bcuz of the bsods).
I'm monitoring the scan % closely right now as I type this msg and it's been stuck at EXACTLY 80% for around 35 min now. Did you try it? (you get the repair option when you try to uninstall avast). I turned to Avast free edition AV (from ESETnod32 AV previously)that I just finished installing and ran the smartscan (default settings) for the second time - as i even reinstalled avast after heeding the advice in other threads i found where they suggested an avast 'repair' might help fix this bug.