Windows 11 23H2 upgrade causing performance loss and trusty Microsoft Defender may be why

This weekend we published a feature looking at the performance improvements, or regressions, one can expect if they were to move from a clean-installed Windows 10 22H2 system to a clean-installed Windows 11 23H2 PC (similar to the one where we upgraded to Windows 11 22H2). What we generally noticed was that the differentials were typically within the margin of error or in the imperceptible zone, though there were situations where one was quite a beat ahead of the other.

Although we haven't yet published our findings showing the differences between Windows 11 22H2 and 23H2 (we plan to do it soon), several users on the internet say they are suffering from performance losses after upgrading to version 23H2.

Reddit user BNSoul opened a thread on the Windows 11 subreddit explaining how they noticed performance regression of around 5 to 8% in several CPU benchmarks. Games also apparently exhibited random stuttering and hitching. They write:

To put it simple[sic], every CPU benchmark shows significantly reduced CPU performance after updating to Windows 11 23H2 from 22H2, even after a fresh/clean install.

 

...

 

I could add an endless list of benchmark results here but just lets say it's always 23H2 5-8% slower in every single one be it single or multi-thread compared to 22H2.

 

Games are also affected with random stuttering, all of this fixed by rolling back to 22H2.

In a separate thread on the Microsoft forum, user Anant Acharya posted about similar performance degradation issues from the CPU side wherein games would randomly drop frames due to the GPU utilization dropping off in those instances. They also report texture loading issues. Curiously, the CPU usage seems to remain the same but the game issues bandwidth-related error messages.

After I had updated to the Windows 23H2 update. I have been noticing sudden stutters and drastic FPS drops in the above-mentioned games.

 

..

 

In newer games like Forza Horizon 5 the GPU utilization (remaining at 92-99 %) suddenly drops to 20-23 percent and the FPS drops from 70-80 to about 10-23, textures not loading. while the CPU utilization remains the same. the game returns a Bandwidth issue warning. as the game was installed on my 7200 RPM hard drive. i decided to move it to my SSD. the issue still existed.

 

..

 

Call of Duty Modern Warfare 2 (campaign remastered) crashed with GPU errors after updating the latest drivers and re-installing windows entirely (still 23H2) the issue presists[sic]. as it has suddenly been brought up and i see no physical signs of damage that may have caused it. and the issue being brought up right after the 23H2 update. i suspect the OS to be the cause.

Several others upvoted this query and also posted their own findings and issues there. Fettman 53 writes:

Unfortunately I have nothing to add, other than that I'm having the same issues. Games I played literally earlier the same day before downloading 23H2 worked flawlessly, and after downloading the OS update, they now run like garbage and have the same issues you listed here. A friend of mine is reporting the same.

David Alfredo, another user who ran several benchmarks, posted:

Same issue here after a clean install of Windows 11 Pro 23H2, I spent a whole day troubleshooting and noticed a CPU performance degradation in all the usual benchmarks (Cinebench, Geekbench, 7-zip built-in benchmark, Corona renderer, OCCT, Super Pi, Y-Cruncher.....) so yeah, it seems like there's something going on with the latest update that affects CPU performance to the point that games now show stuttering. Maybe it's just me but there's not a single CPU benchmark that gets the same or better results on 23H2 compared to 22H2, they all score much lower.

Although the two threads, the Reddit one and the Microsoft forum one, may not stem from the same root cause, there seems to be a solution for the former, which involves resetting the Windows Security app, which seems to resolve the performance problems users may be noticing after upgrading to Windows 11 23H2:

Received an answer from Microsoft after 3 days, they told me to reset Windows Defender through a couple of PowerShell commands

 

(1- "Set-ExecutionPolicy Unrestricted" and

 

2- "Get-AppxPackage Microsoft.SecHealthUI -AllUsers | Reset-AppxPackage") then reboot and enable CPU Virtualization in BIOS (SVM in my X570 BIOS),

 

then in Windows 23H2 open Windows Security and enable Memory Integrity under the Core Isolation settings. Restart and Hypervisor should be running, Virtualization Security will be Enabled and... that fixes the CPU performance issues, CPU now performing as in 22H2 where I had these security features disabled.

 

Tested some benchmarks and games, everything is now ok within margin of error compared to 22H2, GPU benchmarks are 3-5% faster which is nice, games are marginally faster at least CP2077 and SoTR benchmarks, CPU benchmarks on the other hand some performs the same as in 22H2, others improved and a couple of them are maybe 0.2% (margin of error) slower perhaps due to memory integrity being enabled.

Hence, if you are experiencing performance-related issues on your newly upgraded 23H2-based PC, perhaps it's worth a shot to reset Defender.

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