From neowin.net
Just a few days ago we published AV-TEST’s and AV-Comparatives’ findings regarding system performance impact by various anti-malware products. In the article, we covered how Microsoft Defender, AVG, McAfee, and Norton, among others, can hog Windows PCs under different circumstances.
This was just a couple of days after we covered an issue with Microsoft Defender causing performance loss on Windows 11 23H2, where the workaround was to reset Defender. However, if you think third-party anti-virus solutions work flawlessly, you will be quite incorrect.