Microsoft has started switching on a Windows security feature called memory integrity on PCs that didn't have it turned on before. The change is rolling out through regular Windows 11 updates, and it has caused grumbling among some PC gamers, because earlier testing found the feature can cost a few frames per second.
This is a news explainer based on Microsoft's announcements and published reporting, credited at the end. Forge PC hasn't tested how the change affects games on our own hardware, and we don't quote any frame rates of our own.
What's changing
On 1 September 2026, Microsoft's Windows IT Pro Blog announced that from October 2026, Windows quality updates would "begin enabling memory integrity protection on eligible devices". If a PC doesn't already have virtualisation-based security (VBS) turned on, the update turns that on too, because memory integrity is built on top of it.
Microsoft says Windows checks each PC before switching anything on. Its readiness checks look at hardware capabilities, compatibility and performance. The company also says it will respect existing choices: "devices where memory integrity has already been disabled won't be automatically changed by this rollout."
Windows 11's November update, released on 10 November, has brought the change to more people's attention. TechRadar quotes the update's release notes: "This update expands memory integrity protection across eligible devices. Supported PCs may now have memory integrity (HVCI) enabled during updates… while respecting existing user or IT administrator choices." TechRadar says the change is on a gradual rollout, so not every PC will see it straight away.
What memory integrity does
Memory integrity is also called hypervisor-protected code integrity, or HVCI. Microsoft's support page describes it as a feature that "makes it difficult for malicious programs to use low-level drivers to hijack your PC". In its September blog post, Microsoft says it works by "allowing only trusted kernel-mode code and drivers to run", which protects the core of Windows from tampering.
Microsoft also says memory integrity is a foundation for newer Windows features, such as hotpatch updates, which install some security fixes without a restart.
Why some gamers are unhappy
Memory integrity runs part of Windows inside a small virtual machine, and that has a performance cost on some systems. The best-known test is from Tom's Hardware. In March 2023, Jarred Walton tested 15 games on a Core i9-13900K with an RTX 4090 and 32GB of DDR5-6600. Turning VBS off made games up to 5% faster overall in his results, and about 2% faster at 4K ultra settings. The biggest gain was in Microsoft Flight Simulator, at about 10%.
Two things are worth remembering about that test:
It used a very high-end PC in 2023, with a different version of Windows. Walton suggested that less extreme hardware would probably see a penalty in the low single digits.
It's the only controlled test we've cited here. Results vary by game, processor and settings.
TechRadar's coverage makes a similar point. It says older processors are more likely to see a slowdown, and puts the typical hit at perhaps 5%, or maybe 10%, depending on the hardware.
How to check whether it's on
Microsoft's support page for device security explains where to find the setting:
Open the Windows Security app. You can search for it from the Start menu.
Select Device security.
Under Core isolation, select Core isolation details.
Look at the Memory integrity toggle.
Memory integrity needs hardware virtualisation to be turned on in your PC's UEFI firmware (BIOS). On most modern AMD and Intel boards, this is already enabled.
If Windows says it can't turn memory integrity on because of an incompatible driver, Microsoft's advice is to check with the device's manufacturer for an updated driver.
Should you turn it off?
Our advice is to leave it on unless you have a clear reason not to. Memory integrity protects against attacks that try to take over the core of Windows, and Microsoft is clearly treating it as a baseline security setting from now on.
If you think your frame rates have dropped since the November update:
Measure first. Use the same game, the same scene and the same settings, and compare results with the toggle on and off.
Check your drivers. Update your graphics driver and your motherboard chipset driver before deciding anything. Our upgrade guide covers the basics.
Weigh the trade-off. A difference of a few per cent is rarely noticeable on a fast PC. On an older processor, where every frame counts, you may decide differently.
You can turn memory integrity off yourself with the same toggle. Microsoft says the rollout won't turn it back on if you've already disabled it. However, switching it off reduces your PC's protection, so we'd only do it if you've measured a real problem.
What this means for new PCs
If you're building or buying a PC, expect memory integrity to be on by default. TechRadar notes that Microsoft already enabled it on new Windows 11 PCs and new installations before this change. That's not a reason to avoid Windows 11 or a particular processor, but it's another reason to keep drivers up to date. If you're still choosing an edition, our Windows 11 Home vs Pro guide explains that both include the same core security features.
Our verdict
Windows 11 is now switching on memory integrity on eligible PCs through normal updates, unless you've already turned it off. Published testing suggests the cost in games is usually small, with bigger hits possible in some titles and on older hardware. For most gamers, the right move is to leave it on, keep drivers up to date, and only turn it off if your own measurements show a real problem.
