Memory Integrity (Core Isolation) and Gaming Performance: What the Overhead Actually Costs
Turning off Memory Integrity is one of the more persistent "free FPS" tips passed around online. The performance cost is real on some systems and close to nothing on others, and the gap comes down to whether the CPU has hardware acceleration for the underlying security feature.
Memory Integrity, exposed in Windows Security under Core Isolation, is built on Virtualization-Based Security (VBS), a Windows feature that uses the CPU's hardware virtualization capability to run a portion of the OS kernel in an isolated, hypervisor-protected memory region separate from the rest of the operating system. This isolation is specifically designed to prevent a class of attacks where malicious code that gains kernel-level access tries to tamper with critical system code or driver signatures — Memory Integrity checks that kernel-mode drivers haven't been tampered with by verifying them within this protected environment before allowing them to run.
Why isolation has a performance cost at all
Running part of the kernel under hypervisor-enforced isolation means certain operations that would normally execute as direct, unmediated instructions now have to pass through an additional virtualization layer, and specific operations — system calls, some memory management operations, and interrupt handling in particular — incur extra overhead from this indirection. For most everyday computing this overhead is small enough to be imperceptible, but workloads that make heavy, rapid use of exactly these operations, including some games with CPU-intensive draw call patterns or heavy system call usage, can show a measurable frame rate or frame time impact.
Why the impact varies so much by CPU generation
The size of the performance cost depends heavily on how efficiently a given CPU's virtualization hardware handles the specific operations VBS relies on most, and this has improved substantially across CPU generations as manufacturers have optimized virtualization instruction handling in silicon. Older CPU generations without more refined virtualization hardware support have shown meaningfully larger performance hits from Memory Integrity in some CPU-intensive titles — sometimes several percent or more in the most sensitive games — while current-generation CPUs with more mature virtualization acceleration often show a cost close to margin-of-error in the same tests. This mirrors, in a different domain, the same lesson in how a CPU-bound scenario amplifies overhead that would be invisible in a GPU-bound one — the games most affected by Memory Integrity overhead tend to be the same ones that are already CPU-limited rather than GPU-limited, because the additional virtualization overhead lands directly on the CPU side of the pipeline.
Why it's on by default and increasingly hard to disable
Newer Windows installations, particularly on hardware that meets specific security-capable hardware requirements, increasingly enable Memory Integrity and the broader VBS feature set by default, reflecting Microsoft's push toward hardware-backed security as a baseline rather than an opt-in feature. On systems where it's enabled by a hardware or OEM security requirement rather than a simple user toggle, disabling it can require additional BIOS-level changes beyond the Windows Security toggle itself, and on some newer security-focused platform certifications, disabling it may not be fully supported or may re-enable automatically after updates.
Making the actual trade-off decision
For someone chasing maximum competitive frame rates in a specific CPU-sensitive title, testing with Memory Integrity toggled off is a legitimate, low-risk (if reversible) experiment — the setting can be re-enabled at any time with no lasting effect, unlike changes such as disabling security services entirely. The actual gain is worth measuring directly with the specific game and specific CPU in question rather than assuming a fixed percentage from general online claims, since the real number depends heavily on the CPU generation and the specific game's engine behavior. For general use, and for anyone who values the security benefit VBS provides against kernel-level tampering, current-generation hardware has closed the performance gap enough that leaving it enabled is a reasonable default rather than a meaningful sacrifice.