How to Fix High CPU & Memory Usage by 'System and Compressed Memory' in Windows 11 (2026 Guide)

Few Windows processes create more user confusion and performance headaches than 'System and Compressed Memory' (or simply 'System' with process ID 4). Under normal conditions, this operating system mechanism compresses infrequently used pages into RAM rather than writing them to disk. However, in Windows 11 23H2 and 24H2, faulty driver allocations, corrupted pagefiles, and aggressive SuperFetch indexing can cause this process to consume 100% of CPU cycles and lock down 90%+ of physical system RAM.

Why Does 'System and Compressed Memory' Spike to High Usage?

Windows 11 utilizes a memory compression engine inside the NT kernel. When physical RAM fills up, the memory manager compresses stale memory blocks into a compressed memory pool located directly inside RAM. This avoids slow disk read/write paging cycles. However, several system bottlenecks cause the engine to malfunction:

• Memory Pool Non-Paged Leaks: Outdated network drivers (especially Realtek and Killer NIC software) leak non-paged pool memory, forcing the compression manager to continuously attempt compressing uncompressible driver buffers.
• Corrupted Pagefile Allocation: When Windows dynamically resizes pagefile.sys across fragmented SSD clusters, kernel paging threads become locked in an infinite I/O wait state.
• SysMain (SuperFetch) Thrashing: The Windows preloading service repeatedly loads application binaries into standby memory, triggering premature compression cycles.

Method 1: Disable Memory Compression via PowerShell

If your PC has 16GB, 32GB, or 64GB of RAM, you do not need aggressive memory compression. Turning off the compression algorithm stops the NT kernel from burning CPU cycles compressing idle RAM blocks.

1. Right-click the Windows Start button and select Terminal (Admin) or PowerShell (Admin).
2. Check your current memory compression status by entering:

   Get-MMAgent

3. If MemoryCompression is set to True, execute:

   Disable-MMAgent -mc

4. Restart your PC. After rebooting, Task Manager will show the System process CPU consumption drop to 0.1%–0.3%.

Method 2: Rebuild and Set a Static Custom Pagefile

A fragmented or corrupted pagefile causes the kernel memory manager to choke during address translation. Setting a contiguous, fixed-size pagefile eliminates disk thrashing:

1. Press Win + R, type sysdm.cpl, and hit Enter.
2. Navigate to the Advanced tab and click Settings under Performance.
3. Go to the Advanced tab and click Change... under Virtual Memory.
4. Uncheck "Automatically manage paging file size for all drives".
5. Select your primary NVMe SSD (C:), select Custom size, and set both Initial size and Maximum size to 8192 MB (or 16384 MB if running 64GB+ setups). Keeping initial and maximum sizes identical prevents file fragmentation.
6. Click Set, then OK, and reboot your machine.

Method 3: Disable SysMain Service via Services Manager

SysMain (formerly SuperFetch) monitors app launch patterns. On modern PCIe 4.0 and PCIe 5.0 NVMe drives capable of 7,000+ MB/s reads, preloading apps into standby memory is redundant and creates artificial memory pressure.

# Run in Elevated PowerShell to immediately halt and disable SysMain
Stop-Service -Name "SysMain" -Force
Set-Service -Name "SysMain" -StartupType Disabled

Method 4: Fix Non-Paged Pool Leaks via Network Driver Registry (NDU)

Windows Network Data Usage (NDU) contains a documented memory leak bug that fills the non-paged pool over extended system uptimes. Disabling the driver stops memory hemorrhaging:

1. Open Win + R, type regedit, and hit Enter.
2. Navigate to: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Ndu
3. Double-click the Start value on the right pane and change its value data from 2 (Automatic) to 4 (Disabled).
4. Restart Windows 11. Your non-paged memory pool will remain anchored below 400MB.

Frequently Asked Questions