Is Core Isolation (VBS/HVCI) Bad for Gaming? What to Actually Do

Search for Windows 11 gaming tweaks and one instruction appears in almost every list: turn off Core Isolation. It is presented as free performance, an obvious default that Microsoft got wrong. The reality is more interesting and less convenient, so this article takes the question seriously rather than repeating the folklore.

What these acronyms actually mean

VBS — Virtualization-Based Security

VBS uses the CPU's hardware virtualization features to create an isolated region of memory that the normal Windows kernel cannot reach. Think of it as Windows running inside a thin hypervisor, with a small, heavily protected environment running alongside it. Even code with full kernel privileges in the main operating system cannot read or modify what lives in that protected region. VBS is the foundation; it is not a feature you use directly, it is the platform other features are built on.

HVCI — Hypervisor-Protected Code Integrity

HVCI is the feature built on top of VBS, and it is what Windows presents to you as Memory Integrity inside the Core Isolation page. Its job is to verify kernel-mode code before it is allowed to execute, using the protected VBS environment to make that verification itself tamper-proof. The practical effect is that an attacker who has already achieved kernel access still cannot load arbitrary unsigned code into the kernel, which removes one of the most valuable steps in a full system compromise.

Core Isolation and Memory Integrity — the names you see

"Core Isolation" is the section in Windows Security. "Memory Integrity" is the toggle inside it, and it is HVCI. Some systems also show additional items in the same place, such as firmware protection or a kernel-mode hardware-enforced stack protection option, depending on hardware support. When people say "I turned off Core Isolation", they almost always mean they turned off the Memory Integrity toggle.

How to check what your system is doing

Before forming an opinion about the cost, find out whether it is even on. Windows 11 enables VBS and Memory Integrity by default on systems that meet the requirements, and enables it automatically on clean installs on supported hardware, but upgraded systems and machines with incompatible drivers often end up with it off.

That second check is the useful one, because it distinguishes between VBS being available, configured, and actually running. A lot of arguments online are between people whose systems are in different states without either of them knowing it.

So what does it actually cost in games?

Here is the honest answer, without a number attached to it: there can be a cost, it depends on the hardware and the game, and CPU age or feature support alone does not establish its gaming impact.

The mechanism explains the variance. Running the kernel under a hypervisor adds overhead to memory address translation and to certain privileged operations. Hardware features such as second-level address translation and mode-based execution control support virtualization operations. Their presence alone does not establish the performance impact in a game. Hardware support for those features can change how much of the work falls to software, but it does not by itself tell you the effect on your games.

This is why you will find one person insisting the difference is invisible and another insisting it is huge. Different systems can produce different measurements; an anecdote does not establish the effect on your PC. It is also why every blanket claim about the impact — including a specific percentage in a tweak video — should be treated as describing one configuration, not yours.

Two further points that get lost in the argument. First, the cost is not uniform across workloads: The effect can depend on the workload and limiting component; a CPU-bound or GPU-bound classification alone does not quantify it. If you are GPU-bound, the overhead may not surface in your frame rate at all. Second, if you are chasing stutter rather than average frame rate, investigate frame-time spikes with measurements while keeping VBS enabled — the stuttering guide covers shader compilation, thermals and background activity as possibilities to check.

Why anti-cheat has a say in this

This is the part the tweak lists leave out, and it is the part most likely to affect you in practice.

Riot Vanguard, used by Valorant and League of Legends, has publicly required Windows security features including TPM and Secure Boot on Windows 11, and Riot has been explicit that the direction of travel is toward requiring more platform security, not less. Vanguard operates at kernel level precisely because cheats do, and a system with kernel protections disabled is a system where its own guarantees are weaker.

FACEIT Anti-Cheat likewise expects a hardened platform, and its requirements have tightened over time. Players who disable platform security features to chase frames are a recurring support category on both platforms.

The practical consequence is straightforward. If you disable a security feature in pursuit of an unverified performance benefit, and a future anti-cheat update requires it, you do not get a warning — you get a game that will not launch, usually on the evening you wanted to play. That is a bad trade even before considering the security argument. If Valorant is your main game, this alone settles the question; see also Valorant FPS drops and League of Legends FPS drops for the fixes that actually apply to those titles.

What the feature is protecting you against

It is worth knowing what you would be giving up, because "security feature" is abstract enough that people discount it automatically.

HVCI targets a specific and very real attack pattern: bring your own vulnerable driver. An attacker delivers a legitimately signed but vulnerable driver, exploits it to gain kernel execution, and then loads their own unsigned kernel code to install a rootkit, disable security software or steal credentials. This is not theoretical — it is a standard technique, and vulnerable signed drivers are actively catalogued and traded. HVCI breaks the final step: the unsigned kernel code cannot execute, because code integrity checks happen inside a region the attacker cannot reach.

Gamers are not an incidental target here. Game-adjacent software, cheat loaders and modified installers are a common delivery route for exactly this kind of driver abuse. The population that most often disables these protections overlaps heavily with the population most exposed to the attack.

Our recommendation

1. Leave Core Isolation and Memory Integrity on. It is the default for a reason and your anti-cheat expects it. Use measurements to investigate other supported settings.
2. If you doubt it, measure — on your machine, in your game. Do not accept a number from a video recorded on different hardware. Keep Core Isolation and Memory Integrity enabled. Use repeatable frametime captures to compare other supported settings, and compare 1% lows rather than averages.
3. Investigate thermal limits, active background apps, power settings, driver changes and storage activity. Use measurements to determine whether any of them contributes to your frame-time problem. Our Windows 11 gaming settings guide and Windows 11 25H2 performance page cover the ones worth your time.
4. Never disable it because a tweak list said so. If the list cannot explain the mechanism, the cost and the tradeoff, it does not know either.

If an incompatible driver prevents Memory Integrity from being enabled, update, remove or replace that driver so the protection can stay on. Memory Integrity is incompatible with certain older drivers, and Windows will refuse to enable it while such a driver is present.

Where to find Memory Integrity

Keep Memory Integrity enabled. If it is disabled on your PC, enable it in Windows Security → Device security → Core isolation details and restart.

What you would give up by keeping it off:

• Kernel code integrity is no longer verified from a protected environment, which re-opens the vulnerable-driver attack path described above.
• Your anti-cheat may refuse to run now or after a future update, with no advance notice.
• Windows Security will report your device as not fully protected, and may re-enable the feature during a future feature update.

Do not disable Memory Integrity for a performance comparison. Keep it enabled and use repeatable measurements to investigate other causes. That is not a moral position, it is just the correct conclusion from your own data.

Related questions people ask alongside this one

Two neighbouring settings come up in the same breath and deserve a one-line answer each. TPM and Secure Boot are requirements for Windows 11 and for several anti-cheats; leave them on, and note that disabling Secure Boot can prevent Vanguard-protected games from launching entirely. Keep Windows Defender enabled. If scan activity coincides with measured performance problems, investigate scan timing and workload., and if a scheduled scan genuinely overlaps your sessions the answer is to adjust active hours or add a game-folder exclusion, not to turn protection off.

If your frame rate is genuinely low and you are looking for the real cause, the more productive places to start are low GPU usage while gaming, high CPU usage while gaming, and if you are on modest hardware, low-end PC gaming lag. And if you are weighing which tool to use for the cleanup, our honest optimizer comparison lays out the criteria.