Microsoft and Mozilla engineers have fixed a bug in Windows Defender that caused Firefox to increase CPU usage.
Microsoft and Mozilla finally fixed a bug that had plagued Firefox browser users for about five years and caused an increase in CPU consumption in the system. This bug was related to the Windows Defender service and could increase resource consumption several times.
Microsoft and Mozilla engineers have worked together to fix a bug related to Windows Defender and the Antimalware Service Executable, or MsMpEng.exe. This bug caused this browser to consume more CPU than Chrome and Edge. For example, reloading YouTube requires six times more resources on average.
In the image below, you can see the difference between the consumption of processor resources by Firefox, Edge, and Chrome around the beginning of the discovery of this bug. As can be seen, the consumption of Firefox is several times higher than that of competing browsers.
Firefox bug fixes for older versions of Windows have also been released.
Now Microsoft and Mozilla have solved this problem. Firefox developer Yanis Juglart confirmed: “This update will be released as part of regular updates to all users, independent of operating system updates, according to Microsoft. It means that even Windows 7 and 8.1 users will receive it; However, these platforms should not experience any performance issues with Firefox, as the ETW events that cause this issue are not present in these older versions of Windows.”
He later announced that the Windows Defender March 2023 Update had fixed the issue. This update was released on April 4th.
Firefox is also working on more optimizations for CPU resource consumption on Windows. We hope to see these changes in the following updates of this browser. Some time ago, it was announced that Mozilla plans to continue to support these two old operating systems for another year despite the end of Microsoft’s support for Windows 7 and 8.1.