Okay. To save going back on this long thread to where I posted my recommendation and why.
eSet antivirus (not any of their "whole internet" solutions). Just plain, effective av that has the data signatures updates and old signatures are not truncated like with McAfee.
eSet NOD32 for Windows and eSet Cyber Security for macOS.
I used to recommend AVG free but it kept getting slower and slower as their code grew and they failed to properly optimize it.
I'll also repost about how AdBlocker Plus was caught selling bypass access to it's customer base to paying advertisers.
Which is why I dumped AdBlocker Plus and went to uBlock Origins. More than an adblocker, it's more accurate to call it an HTML firewall because you can block content of sites, certain pages on sites, or certain remote content that a site might cross-script to. And it's all GUI point-and-click to do it.
I also highly recommend building yourself a Pi-Hole.
It's easy to do and you can block ANY DNS ping to anywhere so you can block your TV, phone, tablet, etc. trying to "phone home" and send usage data to Samsung (or whomever) for everyone on your network.
Perhaps upgrade your RAM (I have 16GB), best thing you can do to speed everything up and it's cheap. I suspect those with issues haven't got enough overhead. Helps also to have plenty of extra hard drive space as Windows uses it all the time to buffer virtual RAM and swap files. They say 10% free space for swap file space, bump that up to 30% minimum.
We saw performance degradation even on CAD machines with 32Gb of ram. We were savvy enough to understand RAM vs page swapping. I currently have a system with 64Bg of ram and still wouldn't run it.