Firefox engineers discover a Windows Defender bug that causes high CPU usage (bugzilla.mozilla.org)

Article summary

Firefox engineers discovered a Windows Defender bug that causes high CPU usage. The issue is related to the Antimalware Service Executable and occurs when Windows Defender's Real-time Protection feature is active. Microsoft has acknowledged the issue and is releasing a patch to mitigate it. The patch will reduce CPU usage when using Firefox, especially on sites like YouTube.

Main themes

• Windows Defender bug
• High CPU usage
• Antivirus software behavior
• System security
• Firefox optimization
• Microsoft patch

What commenters say

• Windows Defender's bug causes high CPU usage due to excessive computations triggered by Firefox's system calls.
• Antivirus software can be poorly behaved and decrease system security by injecting code into other processes.
• Some users have experienced similar issues with Windows Defender and other antivirus software, suggesting a broader problem.
• The issue is not solely Firefox's fault, but rather a combination of Windows Defender's bug and Firefox's high number of system calls.
• Microsoft's patch will mitigate the issue, but Firefox could also reduce its CPU usage by optimizing its system calls.
• The use of protected processes and memory protection keys could help prevent similar issues in the future.
• The problem highlights the challenges of ensuring system security while allowing antivirus software to function effectively.