Microsoft Defender reduces performance of PCs with Intel processors, but not AMD

Microsoft Defender, the antivirus installed by default on Windows, has an impact on the performance of PCs with an Intel processor. But this problem does not exist on models with an AMD processor.

A performance issue with Microsoft antivirus

First there was a study in May published by AV-Comparatives and another published this week. The May one found that Microsoft Defender was one of the worst antiviruses in terms of resource management.

TechPowerUp (TPU) also discovered similar behavior, but further research revealed that the performance impact could be related to a bug in Microsoft Defender that negatively affects Intel processors, while AMD processors appear unaffected.

TPU discovered that the MsMpEng.exe file, which is the anti-malware service process for Microsoft Defender, consumes Intel processor cycles, which affects performance. The Cinebench R23 rendering benchmark was used to verify this behavior. The behavior is similar to that observed by AV-Comparatives because the system tested in this case was also an Intel system.

Three identical tests were performed in two scenarios, one with real-time protection enabled (Bad) and one with real-time protection disabled (Good). We see that the Intel Core i9-10850K loses about 6% of its performance, which is notable for such a powerful processor. Seeing this, it’s not hard to imagine why Microsoft Defender performed so poorly in AV-Comparatives’ test with an i3, which performs much worse than the i9 here.

A temporary solution exists

So there seems to be a bug in Microsoft’s antivirus, using more resources than necessary. But it is possible to (temporarily) work around the problem by downloading the software Counter Control. It will tell you whether or not your computer is affected by the problem. If error code 0x222 appears, then your computer has the performance issue. Clicking on “Reset Counters” gives the code 0x330, indicating that everything is normal. Unfortunately, you have to do the operation each time you restart the PC.