Windows 10 and Windows 11 don’t need a third-party antivirus app. Each one ships with Windows Security, Microsoft's free built-in protection, and independent tests rate it as highly as the big paid suites. Installing a second antivirus program on top of it will likely make your PC slower and leave it no safer.
Why people still install antivirus out of habit
Early Windows PCs had very little protection of their own. Microsoft didn’t build any anti-malware into Windows until Windows Vista, and even then it was mostly limited to blocking spyware.
Windows 8 brought a more complete antivirus, but Windows 8 never had many users. For most people, built-in antivirus only showed up with Windows 10 in 2015. Ten years of routine had already taken hold by that point: set up Windows, then immediately install antivirus to keep infections away.
Windows doesn’t work that way anymore. The protection now comes included.
How well Windows Security protects your PC
Independent labs test the major antivirus suites against one another on a regular schedule. Protection is one of the measures, and it tracks how well the software actually stops threats. AV-Test publishes these results every few months and scores protection from 1 to 6, with 6 the top mark.
Windows Security’s record since 2020 looks like this:
- A perfect protection score 33 out of 40 times
- Never below 5.5
- An average score of 5.91
- A 99.74% average detection rate for 0-day threats (new threats that don’t have a known fix yet), compared with an industry average of 99.34% over the same stretch
It costs nothing, and you avoid the extra privacy worries that come with putting third-party software on your machine.
Why third-party antivirus can slow your PC
Real-time protection always takes a little performance. When a file gets scanned or an app gets checked as it opens, your PC spends time on that analysis, and it might send something to the cloud for a closer look. In the best case the delay is too short to notice.
Plenty of third-party suites were heavy enough for years that people did notice. Opening a file could bring a visible pause, and apps could take much longer to start. Older and low-power devices feel this the most.
Windows Security holds up well on this front. Across 40 benchmarks it earned a perfect performance score 31 times and averaged 5.83. Its performance scores took a clear hit from a bug in 2022, which has since been fixed.
For browsing speed, opening files and running apps, Windows Security matches the strongest third-party options.
Why third-party antivirus is so noisy
Most third-party suites interrupt you constantly, even when nothing is wrong. Expect update reminders, discount ads, push notifications about new features and more.
Good antivirus should stay in the background and speak up only when something urgent happens, like finding malware. That’s how Windows Security behaves. You’ll usually hear from it when it marks a download as potentially harmful.
The one place Windows Security is slower: installing apps
Installing a new program takes noticeably longer with Windows Security than with competing products. It scans every file the program writes to your drive.
A lot of third-party tools take quicker shortcuts, such as reputation checks or allowlists (lists of software already known to be safe). Those approaches are generally safe, though less thorough.
Most people come out ahead with the slower method, since clever malware exists and a thorough scan catches more of it. You probably don’t install new software very often anyway. Someone who tries out new apps all the time might install two on a workday and one on a weekend day, so slower installs shouldn’t change much about how you use your PC day to day.
What third-party antivirus companies offer now
Third-party antivirus companies are still around, though one company now owns most of the free options. Their products compete less on virus protection these days and more on extras like identity protection, phishing protection and dark-web monitoring.
A third-party suite could still make sense if you want those extras. If all you need is antivirus protection, Windows Security covers it.
Frequently asked questions
Does Windows 11 have built-in antivirus?
Yes. Windows 11 and Windows 10 both come with Windows Security, which gives you antivirus protection with nothing extra to install.
Is Windows Security as good as paid antivirus?
AV-Test results since 2020 give it an average protection score of 5.91 out of 6 and a 99.74% detection rate for 0-day threats, higher than the 99.34% industry average.
Why is installing programs slow with Windows Security?
It scans each file a new program writes to your drive. Many third-party tools rely on quicker but less thorough checks, such as reputation or allowlists.
Does Windows Security slow down my PC?
Not much in everyday use. Its performance score averaged 5.83 out of 6 across 40 benchmarks, and the 2022 bug that dragged its scores down has been fixed.