Avast Antivirus historically has one of the highest rates of false positives of all antivirus products tested by AV-Comparatives. Avast Antivirus also has a history of connecting with Google servers to send analytics. The latest version of Avast Antivirus defaults to inserting a promotional advertisement into your outgoing emails. That's the final straw.

Please recommend a (free for personal use) tool for that meets the following requirements:

  1. Low CPU use during real-time scanning
  2. Low memory use
  3. High rate of detection
  4. Low rate of false positives
  5. No inserting ads into outgoing emails
  6. No intrusive advertising popups or nags on the desktop or system tray
  7. On-demand and real-time scanning
  8. No (or minimal) extra bulk
  9. Can be uninstalled cleanly
  10. No connecting to Google Analytics or other similar operations

I am not concerned about CPU use during on-demand scanning.

This question is open to answers for any version(s) of Windows. Compatibility with every version (such as XP) is not required.

Based on these simple requirements, the following do not qualify (based on current AV-Comparatives testing): Avast, AVG, Trend Micro, Baidu, F-Secure, ThreatTrack Vipre, Fortinet, Panda, Quick Heal, Lavasoft, and BullGuard.


Currently testing Avira Antivirus on that system. It has excellent ratings and could possibly meet the requirements. Unfortunately, it seems to have a serious issue. See this SuperUser QA for details.


Avira Antivirus appears to be "scareware": almost every time you boot, it displays a message trying to scare you into buying their premiere product. It may display these banners at other times as well.

  • Being a former Avast user who stopped when it turned to scareware, I have switched to ESET NOD32, not gratis though, but I'm happy with it. – Thomas Weller Nov 19 '15 at 23:02
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    @ThomasWeller Avast being "Scareware": I've noticed that too. Their intrusive promotions definitely try to scare users into spending their money. – RockPaperLz- Mask it or Casket Nov 19 '15 at 23:18
  • Whilst I cannot speak from too much experience, I would recommend either Malware Bytes (although can appear quite feature-less) or Avira. > Blockquote – DankyNanky Nov 20 '15 at 10:16
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    Avast just destroyed my windows upon uninstall (windows updates was installed at same time) and I get 0x00000255 or something upon boot. Another avast just haven't detected some yessearch "virus" installation upon installing some tool for usb formatting. Never will use avast again... – llamerr Jan 13 '16 at 15:07
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    @RockPaperLizard - Have run into similar problems with avast especially what appear to be an exponential increase in false positives since having run a scan with Malware-Bytes, no such detection was found. How did you get on with you testing? – Motivated Jan 31 '16 at 6:05

This is just for general use. I would recommend MalwareBytes Anti-Virus. It's a powerful tool. It has one of the most up-to-date databases in whole spectrum of malware tools. It uninstalls almost with no leftover which is real handy.
The paid version has real-time scanning, but it's not meant to be used in a way where you need it.
Its a real gem as it comes to free malware tools. It only pops up when it found something.
When you are actively scanning it take up a ton of RAM, but it speeds up the time.

But this scanner is better as a side virus scanner. I would pick this one with Windows Defender with Windows updates turned on.

It fits almost all your needs on the free version.


Windows 8 and 10 have a built-in virus scanner called Windows Defender, accessible in the Windows Security app. (Previous versions of Windows can download Microsoft Security Essentials while they are still supported.) It is free and doesn’t have any ads. It is also well-integrated with Windows, so it shouldn’t take up many resources.

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