Microsoft fixes Defender's 5-year-old BUG: causes Firefox Firefox CPU to be overoccupied

Thanks to CTOnews.com netizen Coje_He for the clue delivery! CTOnews.com, April 8, Microsoft finally fixed the BUG in Windows Defender, causing the CPU to be overused when used with Firefox browser Firefox. This BUG has been around for 5 years and has not been fixed until now.

When users enable Firefox browsers to surf the Internet, Windows Defender will enable the Antimalware Service Executable feature, resulting in a significant increase in CPU usage.

Many Firefox browser users report that there will be slow response, stutter and so on in the process of use. CTOnews.com queried Bugzilla and found that the BUG was reported as early as May 2018, and both Win10 and Win11 platforms were affected.

Mozilla engineers say the problem is caused by Msmpeng.exe (Microsoft malware Protection engine) in Defender. Compared with Chromium-based browsers such as Chrome and Edge, Firefox browsers take up five times more CPU.