For a modest Windows 11 PC, McAfee, Kaspersky, and ESET had the lowest measured impact in AV-Comparatives’ April 2026 low-end test. Avast and AVG also ranked near the top, while AV-TEST’s separate August 2026 assessment gave Avast, AVG, and ESET full marks for protection, performance, and usability. These results make a useful shortlist—not a guarantee of how any product will feel on your particular computer.
Which antivirus is lightest on a modest PC?
In AV-Comparatives’ April 2026 Consumer Performance Test (low-end), McAfee Total Protection had the lowest combined impact score, followed by Kaspersky Premium and ESET HOME Security Essential. A lower score means less measured impact within this specific test; it does not mean stronger protection.
The lab tested consumer products with default settings and an active internet connection on an up-to-date 64-bit Windows 11 PC with an Intel Core i3, 8 GB of RAM, and an SSD system drive. Tests covered file operations, installing and launching applications, downloads, web browsing, and office productivity. The report says its performance test measures relative system impact, not protection effectiveness. Scores are not seconds lost and cannot predict an individual PC’s exact slowdown.
| Product and tested version | Combined impact score | What the result says |
|---|---|---|
| McAfee Total Protection 1.37 | 3.3 | Lowest measured impact among these products in this test. |
| Kaspersky Premium 21.24 | 3.5 | Second-lowest measured impact. |
| ESET HOME Security Essential 19.1 | 4.2 | Third-lowest measured impact. |
| Trend Micro Internet Security 17.9 | 4.7 | Among the lower-impact results. |
| Norton Antivirus Plus 26.3 | 5.3 | Lower impact than Avast and AVG in this test. |
| Avast Free Antivirus 26.3 | 5.5 | Near the top of the low-impact group. |
| AVG Antivirus Free 26.3 | 5.5 | Same measured score as Avast. |
| Bitdefender Total Security 27.0 | 9.6 | Higher measured impact than the products above. |
| Microsoft Defender Antivirus 4.18 | 12.9 | Highest measured impact among the listed products in this test. |
Do not confuse the combined impact scores with the report’s separate Procyon result: Microsoft scored 97.1 against a baseline of 100 on that different scale. The figures above are for the specific versions and conditions identified by AV-Comparatives, not a general ranking of every version or configuration.
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Which lightweight antivirus also scored well for protection?
Performance and protection are different questions. AV-Comparatives explicitly says its performance test does not evaluate how effectively a product protects a device. In AV-TEST’s August 2026 Windows 11 consumer assessment, conducted during July and August using current publicly available product versions, Avast Free Antivirus 26.6, AVG Antivirus Free 26.6/26.7, and ESET Security Ultimate 19.1/19.2 each received 6/6 for protection, 6/6 for performance, and 6/6 for usability. Microsoft Defender Antivirus received 6/6 for protection, 5.5/6 for performance, and 6/6 for usability.
Those AV-TEST ratings use that lab’s own test setup and scale; they are not directly comparable to AV-Comparatives’ low-end impact scores. They provide a separate check on protection and usability, rather than proof that one product will be fastest on your machine.
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Shortlist: which product should you consider?
ESET: a strong all-round candidate
ESET combines a low 4.2 impact score in the April 2026 low-end test with full protection, performance, and usability marks for ESET Security Ultimate in AV-TEST’s August 2026 Windows 11 assessment. The products and versions differ between tests, so this is supportive evidence rather than a single combined head-to-head result.
Avast or AVG: strong options with free editions tested
Avast Free Antivirus and AVG Antivirus Free each scored 5.5 in the low-end test, and both received full marks across AV-TEST’s three categories. These results make them worth comparing if you want to consider a free product as well as paid suites. Check the current edition’s features and compatibility before installing; lab scores do not establish subscription terms or the experience of every version.
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McAfee or Kaspersky: lowest impact in the low-end ranking
McAfee Total Protection and Kaspersky Premium recorded the two lowest combined impact scores. That makes them compelling candidates when measured impact is your first filter, but the figures alone do not establish protection quality. Check current independent protection results for the exact product and version you are considering, and weigh whether you want a broader security suite.
Microsoft Defender: a built-in baseline, not a reason to ignore support
Microsoft Defender is relevant if you use a supported Windows installation and prefer the built-in protection. Its AV-TEST August 2026 protection and usability ratings were full marks, while performance was 5.5/6; its combined impact score in AV-Comparatives’ low-end test was 12.9. Different labs and methods produced these measures, so use them as separate context rather than a contradiction.
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Other tested choices
Trend Micro and Norton also had relatively low scores in AV-Comparatives’ test, at 4.7 and 5.3. Bitdefender’s score was 9.6 in that test. These impact figures do not establish a protection ranking; assess protection separately and verify that the specific product remains compatible with your Windows version.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Check Windows support before choosing antivirus
Antivirus cannot replace operating-system security updates. Microsoft ended ordinary Windows 10 support on October 14, 2025: standard support no longer includes ordinary technical assistance, feature updates, or security updates. Eligible consumer devices may enroll in Extended Security Updates (ESU) through October 12, 2027, subject to Microsoft’s eligibility and enrollment conditions. See Microsoft’s Windows 10 support guidance.
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Before installing an antivirus on an older computer, identify its Windows edition and version, then confirm current compatibility on the vendor’s product page. A Windows 11 test does not establish support for Windows 10, Windows 8.1, or older systems.
Microsoft’s published Windows 11 minimums include a supported processor running at 1 GHz or faster with two or more cores, 4 GB of RAM, and a storage device of at least 64 GB. AV-Comparatives’ low-end test used 8 GB of RAM and an SSD, so a PC that barely meets Windows 11’s minimums may behave differently. Full requirements are listed on Microsoft’s Windows 11 system requirements page.
How to choose and check impact on your own PC
- Confirm the operating system. Check your Windows edition and version, and whether it still receives security updates or is covered by an applicable ESU enrollment.
- Check vendor compatibility. Use the vendor’s current product page to verify support for your precise Windows version and hardware before you install or pay.
- Use lab results as a shortlist. Compare low-end performance results for system impact, then review separate protection results instead of treating speed as security.
- Try it during normal use where a trial is offered. Compare your usual tasks—such as startup, opening everyday apps, browsing, and file work—with the product installed. Background apps, settings, hardware, and software conflicts can change perceived speed.
- Keep the configuration simple. Extra suite features can add complexity. Install only what you want and check for conflicts with other security software already on the PC.
There is no reliable universal answer to “Which antivirus is light on CPU?” The cited low-end report combines results across several everyday activities; it does not establish a CPU-only ranking. Its scores are best used to narrow the field, followed by checking protection, operating-system compatibility, and the experience on the actual computer.
How to read older annual awards
AV-Comparatives’ 2025 annual summary, released January 14, 2026, awarded overall performance Gold to Avast and AVG, Silver to Norton, and Bronze to McAfee. It named Avast, AVG, Bitdefender, ESET, G Data, Kaspersky, and Norton Top-Rated in its consumer test series; ESET received Advanced+ in all seven tests and Gold for Advanced Threat Protection. These awards summarize the January–December 2025 test cycle. They add context, but do not replace the more recent April 2026 low-end impact results or establish current product support.
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