Why Windows 11 Memory Compression Slows Down Your PC

Quick fix: Open Terminal (Admin) and run Disable-MMAgent -mc to disable memory compression. Reboot. Use this only if you have 16+ GB RAM and notice CPU usage spikes when memory fills — compression trades CPU for memory savings.

Task Manager shows Memory at 80%+ but you have plenty of RAM. The Compressed value in the Memory tab is several GB. Sometimes the PC feels sluggish during heavy memory use even though physical RAM isn’t exhausted. Windows’ memory compression keeps less-frequently-used pages compressed in RAM instead of paging them to disk — but the compression itself uses CPU, and on systems with abundant RAM it can be slower than just keeping pages uncompressed.

What causes this

Windows’ Memory Compression replaces traditional page-to-disk swapping with in-RAM compression. When memory pressure rises, instead of writing inactive pages to pagefile.sys, Windows compresses them in RAM using algorithms like XPRESS. This trades CPU time for memory capacity — useful on RAM-constrained systems (4 GB, 8 GB) where avoiding disk I/O is worth the CPU cost. On 16+ GB systems with NVMe SSDs, the trade-off inverts: you have plenty of RAM, your SSD is fast enough that paging isn’t slow, and the CPU spent compressing/decompressing is more valuable than the memory saved.

Method 1: Disable memory compression via PowerShell

The supported control.

1. First check current state:

   Get-MMAgent

   Look for MemoryCompression: True (compression on) or False (off).

2. Open Terminal (Admin).
3. Disable memory compression:

   Disable-MMAgent -mc

4. Verify with Get-MMAgent — MemoryCompression should now be False.
5. Reboot. The change applies on next boot.
6. Open Task Manager → Performance → Memory after reboot. The Compressed value should be 0 MB.

To re-enable later: Enable-MMAgent -mc, reboot.

Method 2: Use full disk paging instead of compression

When you disable memory compression, Windows reverts to traditional pagefile swapping. Make sure pagefile is configured well.

1. Open Settings → System → About → Advanced system settings → Performance → Settings → Advanced → Virtual memory → Change.
2. For systems with 16+ GB RAM and fast NVMe SSD: untick Automatically manage paging file size. Set Custom Size: Initial = 2048 MB, Maximum = 8192 MB.
3. For systems with 32+ GB RAM: set Initial = 1024 MB, Maximum = 4096 MB. With abundant RAM, the page file is rarely touched.
4. Click Set → OK. Reboot.
5. The combination of disabled memory compression + appropriately-sized pagefile gives you straightforward memory behavior: pages stay in RAM unless real pressure hits, then they go to disk.

This is the right pairing — compression off, pagefile tuned for occasional use.

Method 3: Reduce SuperFetch / SysMain to lower memory pressure

An alternative to disabling compression — reduce what fills the RAM in the first place.

1. SysMain (SuperFetch successor) preloads frequently-used apps into RAM. This raises the working set and triggers memory compression sooner.
2. Open services.msc. Find SysMain. Right-click → Properties.
3. Set Startup type to Disabled. Click Stop.
4. Click Apply → OK.
5. This frees several GB of RAM that would otherwise be used for prefetch. The compressed memory value drops correspondingly.
6. On SSDs, SysMain provides negligible benefit anyway. Disabling it is a reasonable tweak independent of memory compression.

Combined with Method 1 (disabled compression), this gives the cleanest memory behavior on a RAM-rich SSD system.

How to verify the fix worked

• Open Task Manager → Performance → Memory. The Compressed value should be 0 MB (or near 0) after reboot.
• Total memory usage may rise slightly because compressed pages now stay uncompressed in RAM — that’s expected and fine on RAM-rich systems.
• CPU usage at idle should drop slightly — compression/decompression CPU is no longer running.
• Run Get-MMAgent | Select MemoryCompression, PageCombining in PowerShell. MemoryCompression: False.

If none of these work

If memory compression persists despite Disable-MMAgent, or if performance doesn’t improve, three causes apply. Group Policy override: corporate-managed PCs may enforce memory compression. Check gpresult /h C:\gpresult.html for memory-related policies. Real memory pressure: if your RAM is genuinely insufficient for your workload (8 GB while running 50 Chrome tabs + IDE + Docker), compression is helping — disabling it just shifts the pressure to slower disk paging. Add more RAM instead. SSD wear: if you disabled compression and the pagefile is now heavily used, monitor SSD wear with CrystalDiskInfo. Modern NVMe SSDs handle pagefile writes fine, but very budget SSDs may degrade faster. For most 16+ GB systems on quality SSDs, disabled compression produces faster, more predictable behavior — which is why power users often turn it off.

Bottom line: Memory compression trades CPU for memory. On 16+ GB systems with NVMe SSDs, the trade is no longer worth it — disable with Disable-MMAgent -mc and reboot. CPU drops, memory behavior becomes more predictable.