Computer Virus revisited

Couldn't figure out why all the sudden my Computer slowed to a crawl and at times wouldn't connect to some sites(FABO ) being one. I've had this Laptop for over 3 years now and have just relied on Windows Defender to keep me running. After it slowed down I ran 3 virus scans with nothing found. Used free version of AVG to find 1 piece of Malware which was removed. It was still slow so I started poking around in My Control Panel and found a recent download I didn't recognize and Googled it. Sure enough it was a known Virus and as soon as I got it uninstalled and rebooted My Laptop it's running like a top again. The name was ober version 1.6444. I no longer trust Windows to protect me but every free Virus I ever used slowed my computer down. Any suggestions ? No, I won't ditch Windows :)
Switch to one of the many free Linux OSs. Peppermint?