Microsoft Fixes Years Old Bug In Firefox Using High CPU Usage

There is good news for Firefox users who have been wondering about performance issues on Windows 10 or Windows 11 for years: Mozilla is now reporting this known annoyance as fixed after around five years.

This is reported by the online magazine the performance problems first appeared in 2018 with Firefox users who use Defender and were therefore still using Windows 10 at the time. The reports were very similar – you could always read about performance losses that were clearly noticeable.

The Mozilla developers found the cause to be that Defender didn’t work particularly well with Firefox – as soon as Firefox was started, Defender was particularly active and, according to the task manager, needed 30 percent or more of the processor’s performance. This slowed down Firefox.

Microsoft definition update fixes the problem

This annoyance has now dragged on for years and even switching to Windows 11 hardly brought any change in behavior. According to Heise, however, Microsoft has now created the solution to the problem in one of the regular definition updates. The definition update is equally available for all OS versions. In the Mozilla forums, a user wrote:

“According to Microsoft, this will be made available to all users as part of regular definition updates that are packaged independently of OS updates. This even includes users of Windows 7 and 8.1, although these platforms don’t even experience the performance issue with Firefox should have because the ETW events that cause it doesn’t exist on those older versions of Windows, so as far as I know only users who explicitly decline definition updates (which doesn’t sound like a sensible solution for your AV) get the fix.”

Once the update has been installed, Firefox users should notice the improvement in their everyday lives.