Is Microsoft Defender Enough for Windows 10 and 11? AV-Test Results, Paid Antivirus Trade-Offs

Here's what checks out, what needs correcting, and how to tell which antivirus your PC is actually running.

The claim: free protection is now enough​

Innovation Village's reasoning goes like this:

• Microsoft has shipped built-in antivirus with Windows since Windows 8 in 2012.
• Defender has gone from bottom of the lab charts to top marks.
• Third-party vendors now give away core antivirus and charge for extras like VPNs, cloud backup and parental controls.
• For most users those suites add nagging pop-ups, duplicate features and some performance cost.

The column doesn't say paid suites are worthless. It says they can be useful guardrails when you set up a PC for a less tech-savvy relative who can't easily spot phishing or fake download buttons. It also suggests keeping a free on-demand scanner such as Malwarebytes for a second opinion now and then.

Section summary: The argument is about not paying for a second real-time antivirus on an ordinary home PC. It isn't advice to drop security software altogether.

Defender's comeback, checked against the lab data​

The 2015 low point​

Innovation Village says Defender scored 0.5 out of 6 for protection in AV-TEST's May–June 2015 testing. That's accurate. AV-TEST's archived report for Windows Defender 4.7, tested on 64-bit Windows 8.1, shows that score. Detection of widespread malware was 88.5% in May and 95.2% in June. In the real-world zero-day test it caught 90.2% and 84.7%, against an industry average of 98.2%.

Keep in mind that this was a different product version on a different Windows release. It's useful history, not a direct comparison with today.

The 2026 numbers, and one correction​

The recent results are strong. AV-TEST's detailed report for Microsoft Defender Antivirus (Consumer) 4.18 covers July–August 2026 on Windows 11 Professional (English), (64-Bit):

• Real-world 0-day testing (web and email threats included): 297 samples used. Defender blocked 100% in both July and August, against an industry average of 99.9%.
• Widespread malware reference set: 12,543 samples used. Defender again scored 100% in both months, matching the 100% industry average.
• Protection score: a full 6.0 out of 6.0.

So the detection figures Innovation Village quotes are right. The "flawless 6-out-of-6" wording needs a qualifier. AV-TEST scores products on protection, performance and usability, six points each. In this round Defender got 6/6 for protection, 5.5/6 for performance, and 6/6 for usability. That's 17.5 out of 18, which meets AV-TEST's "TOP PRODUCT" threshold of 17.5. It isn't a perfect score.

The context also matters. AV-TEST's summary table for the same round gives full 6/6/6 marks to Avast Free Antivirus, AVG Antivirus Free, Bitdefender Total Security, Malwarebytes Premium, McAfee Total Protection, Norton 360 and others. Defender tied the best on protection and came in half a point behind several rivals on performance. It's at the top level, but it isn't ahead of everyone.

Not a one-off​

The more convincing evidence is consistency. AV-TEST's Microsoft archive lists Defender Antivirus (Consumer) 4.18 as a Top product across many recent test rounds, including June and August 2026. A product that scores well round after round is more trustworthy than one good result.

Section summary: Defender's protection results are top-tier and consistent. Its overall score was 17.5 of 18, not a clean sweep, and it ranked slightly behind some paid and free rivals on performance.

What Defender does out of the box​

Microsoft's support documentation confirms the basics Innovation Village describes:

• Defender Antivirus is built into Windows 10 and Windows 11.
• Real-time protection scans files and programs as they're opened or run.
• Security intelligence (definitions) downloads automatically through Windows Update. You can also force a check under Virus & threat protection updates > Check for updates.
• If you have no other security product, or yours has expired, Defender turns itself back on automatically.

Microsoft also documents scan options beyond the always-on protection:

• Quick scan: checks the places malware most often hides.
• Full scan: checks every file and program. Microsoft recommends it if you think your PC is infected, and notes the PC may run a bit slower while it works.
• Microsoft Defender Antivirus (offline scan): restarts the PC and scans from the Windows Recovery Environment without loading Windows, which makes it harder for persistent malware to hide. Save your open files first.

In File Explorer you can also right-click a file or a removable drive and choose Scan with Microsoft Defender.

The "it disables Defender" claim, clarified​

Innovation Village says installing a third-party antivirus automatically switches off Defender's real-time scanning. Microsoft's wording is more specific: Defender Antivirus turns itself off when you install a compatible non-Microsoft antivirus program. That's intentional. Microsoft advises against running more than one real-time antivirus or antispyware product at once. Its FAQ says doing so can affect performance and can cause update or install errors such as 0x80070643.

This is a good reason not to stack products. It doesn't mean Windows Security as a whole goes away. Microsoft says on-demand tools like the Microsoft Safety Scanner and Microsoft Defender Offline can sit alongside any real-time product, because they only run when you start them or schedule them. A second-opinion scanner, used occasionally, works the same way.

The performance argument has a gap​

To back the "performance hit" point, Innovation Village cites Tom's Guide's October 2026 benchmarks. Its numbers match the Tom's Guide data. The test PC had an AMD Ryzen 7 7700X, an MSI RTX 5070 Ti and 32GB of DDR5. Cyberpunk 2077 ran at Ultra settings and Forza Horizon 5 at High.

Three caveats:

1. Defender wasn't tested. The table shows that some third-party scans cost frame rate. It says nothing about whether Defender costs less. In AV-TEST's everyday-use performance testing, Defender actually scored 5.5, below the 6.0 for Malwarebytes Premium and Bitdefender Total Security.
2. The baseline already had the antivirus running. Tom's Guide measured baseline frame rates with the security software open but idle, so the numbers show what an active scan costs, not what having the product installed costs. Tom's Guide did note that Malwarebytes appeared to drag performance down even when idle.
3. Tom's Guide drew a different conclusion. Its takeaway was that turning off your antivirus before gaming is a habit you can drop. Avast, Bitdefender and Norton showed barely noticeable drops in Forza. The bigger surprise was network speed: Malwarebytes' upload speed fell 25.8% during a full scan, and Avast's download speed fell 18.5%.

A fair reading: a full scan can cost frame rate with some suites on some hardware, and how much depends heavily on the product. It's a reason to choose carefully. It isn't proof that every third-party antivirus slows a gaming PC.

Section summary: The fps figures are real, but they show differences between third-party suites, not that Defender is faster.

Where the column overreaches​

Some of Innovation Village's points are opinion presented as fact:

• "Bundled VPNs and password managers lag far behind standalone services." That may be true for specific products, but no single comparison here supports it for every suite. Judge each bundle on its own merits.
• Product tier details, such as Malwarebytes reserving advanced anti-exploit and ransomware protection for its premium tier, or Norton 360 Deluxe including a VPN, 50GB of cloud backup and parental controls. These are Innovation Village's descriptions. Vendors change their plans often, so check the current plan page before you buy or cancel.
• Social engineering. Innovation Village is right that today's main threats are fake invoices, credential-harvesting login pages and tech support scam pop-ups. But no antivirus, free or paid, reliably stops you from typing your password into a convincing fake page. Edge's Microsoft Defender SmartScreen helps block potentially unwanted apps and warns about reported malicious sites. Your judgment is still the last line of defense.

Microsoft's own guidance covers the same ground: download apps from trusted sources such as the Microsoft Store, keep Windows, your browser and your apps updated, and use a modern browser like Edge with SmartScreen.

How to switch to Defender safely​

If you're thinking about cancelling a paid suite, don't uninstall first and check later. Do it in this order:

1. See what's protecting you now. Search Start for Windows Security, open Virus & threat protection, and look at which provider is active.
2. Decide whether you need the extras. If you rely on the suite's VPN, backup, password manager or parental controls, set up replacements before the subscription ends.
3. Uninstall the third-party product with its own uninstaller or through Settings' installed apps list. Restart the PC.
4. Confirm Defender is on. In Virus & threat protection settings, check that Real-time protection is on. Microsoft also recommends turning on Cloud-delivered protection and Automatic sample submission for the best protection. Sample submission sends suspicious files to Microsoft for analysis, so it's a privacy trade-off to make on purpose.
5. Update and scan. Run Check for updates under protection updates, then run a full scan.
6. Consider extra hardening. Tamper protection stops other apps from changing key Defender settings. Controlled folder access, under Ransomware protection, blocks untrusted apps from changing protected folders such as Documents, Pictures and Desktop. Don't assume it's already on, and expect to approve some legitimate apps when you first enable it.

What success looks like: Windows Security lists Microsoft Defender Antivirus as the active provider, real-time protection is on, definitions are current, and a full scan comes back clean.

Common problems and fixes​

• Error 0x80070643 or failed updates: this often means two real-time products are installed. Remove the leftover one, restart, and try again.
• Real-time protection won't turn off: if tamper protection is on, you have to turn it off before you can turn off real-time protection. Turning real-time protection off is rarely a good idea anyway; for a single file or folder, Microsoft recommends adding an exclusion instead.
• A threat was "partially removed": Microsoft suggests running the Malicious Software Removal Tool (press Windows + R and run %windir%\system32\mrt.exe), restarting, installing the latest updates, and running Microsoft Defender Offline if the problem persists.
• A full scan freezes the PC: update your apps, install the latest definitions, and close unneeded programs while the scan runs.
• Defender won't update at all: Microsoft lists malware tampering, Windows Update problems and unsupported Windows versions as possible causes. An unsupported Windows install is a serious risk no matter which antivirus you use.

Who should still pay​

A paid suite still makes sense if:

• You want one bill and one dashboard for antivirus, VPN, backup and identity monitoring, and you've confirmed the bundled tools are good enough.
• You're managing a family PC and want parental controls or tighter restrictions.
• You've compared a specific product's track record and prefer it, which is reasonable since several third-party products matched or slightly beat Defender's overall AV-TEST score.

Business devices are a separate case. Microsoft describes Defender for Endpoint as its product for protecting corporate devices. A managed fleet should follow the organization's security policy, not consumer advice.

Verdict​

Innovation Village's central point is right: on an updated Windows 10 or Windows 11 home PC, paying for a second real-time antivirus just for malware protection is hard to justify. Defender's protection scores have been top-tier for many test rounds.

The column's supporting points need adjusting. Defender's latest AV-TEST result is 17.5 of 18, not perfect. The gaming benchmarks it cites never tested Defender. Antivirus of any kind can't protect against a password typed into a phishing page.

If you keep Windows updated, leave Defender's protections on, download carefully, and run an occasional on-demand second-opinion scan, you can probably cancel that renewal.