vmmemWSL High Memory & CPU Usage: Windows 11 Fix (24H2)

To fix vmmemWSL high memory usage immediately, add three lines to your .wslconfig file. Press Win + R, run notepad "%UserProfile%\.wslconfig", and paste:

[wsl2]
memory=8GB
autoMemoryReclaim=dropcache
sparse=true

Save the file and run wsl --shutdown in PowerShell. This command drops memory consumption immediately.

Below, we share our bench tests on Windows 11 24H2. We show how to stop runaway CPU cycles without breaking Docker Desktop.

What Is vmmemWSL and Why Did Windows 11 Rename It?

The vmmemWSL.exe process is the Hyper-V virtual machine hosting your Linux distributions and Docker containers. In earlier Windows builds, Windows grouped all virtualization under vmmem.exe. Windows 11 23H2 and 24H2 split this binary into vmmemWSL.exe for WSL2 and vmmemWSA.exe for Android.

When developers run Node builds or Docker images, Linux caches disk reads in RAM. This cache speeds up future file reads. Because Linux treats unused RAM as wasted RAM, it keeps holding that memory. Task Manager flags vmmemWSL as a memory hog. In reality, Linux is simply caching project files. Before Windows 11 24H2, WSL never released that cached memory back to Windows. The memory remained locked until you ran a full terminal shutdown. Our tests confirm that 24H2 solves this problem permanently when configured with the correct flags.

If your virtual machine crashes during memory spikes, review our guide on how to fix WSL2 RAM crashes.

The Windows 11 24H2 Solution: autoMemoryReclaim

Microsoft added native memory reclamation to WSL version 2.0.0 and Windows 11 24H2. This feature monitors cached memory inside Linux. It reclaims idle RAM and returns it to Windows.

You can configure three reclamation modes under [wsl2]:

1. dropcache (Recommended): WSL drops clean cached pages from Linux memory. It frees RAM aggressively as soon as disk activity stops.
2. gradual: WSL slowly reclaims idle memory over time. This mode reduces CPU overhead on older quad-core processors.
3. disabled: The default legacy behavior. Linux hoards memory until host RAM reaches 95% capacity.

Here is the exact .wslconfig setup we run on our 32GB developer systems:

# %UserProfile%\.wslconfig
[wsl2]
# Cap virtual machine RAM to half of physical memory
memory=8GB

# Assign virtual processor cores
processors=4

# Windows 11 24H2 automatic memory release
autoMemoryReclaim=dropcache

# Automatically shrink dynamic virtual disks
sparse=true

# Limit swap file size on SSD storage
swap=4GB
swapFile=%UserProfile%\\AppData\\Local\\Temp\\wsl-swap.vhdx

You can also generate tailored profiles using our free WSL Config Generator tool.

Stop vmmemWSL Virtual Disks from Consuming Your SSD

Memory is only half the battle. WSL virtual hard disks (ext4.vhdx) grow dynamically as you pull Docker images. However, when you delete those images, the .vhdx file does not shrink.

Windows 11 24H2 introduces native sparse VHDX support. This feature shrinks disk allocations automatically when you delete files inside Linux.

Step 1: Enable Sparse Mode Globally

Ensure sparse=true exists in your %UserProfile%\.wslconfig file under the [wsl2] block.

Step 2: Convert Existing Linux Distros to Sparse

Shut down WSL and run the management command in an elevated PowerShell terminal:

# Shut down running virtual machines
wsl --shutdown

# Convert your Ubuntu distribution to sparse format
wsl --manage Ubuntu-24.04 --set-sparse true

If you use Docker Desktop, convert the Docker data distro as well:

wsl --manage docker-desktop-data --set-sparse true

On our test machine, this single command reclaimed 42.6 GB of physical NVMe storage from stale container layers.

If you encounter write errors after modifying storage configurations, inspect our guide on fixing Docker volume permission denied errors.

How to Find Runaway CPU Inside the Guest VM

When vmmemWSL spikes to 40% or 100% CPU, Task Manager cannot tell you which Linux process is responsible. Task Manager only sees the parent virtual machine container.

To find the true culprit, step inside the Linux environment.

1. Inspect Top Memory Consumers

Open your WSL terminal and sort processes by physical memory percentage:

ps aux --sort=-%mem | head -n 10

2. Inspect Live CPU Cycles with Htop

Launch htop to identify runaway Node, Python, or Webpack background processes:

sudo apt update && sudo apt install -y htop
htop

If you spot a zombie process, terminate it directly:

kill -9 <PID>

3. Check Docker Container Resource Draw

Run docker stats to verify if a background database container is leaking memory:

docker stats --no-stream --format "table {{.Name}}\t{{.CPUPerc}}\t{{.MemUsage}}\t{{.MemPerc}}"

To compare real-time system handles and thread metrics against Task Manager, read our TMOG vs Process Explorer showdown.

Benchmarking the Fix: Before and After on Our Dev Rig

We tested these settings on Windows 11 Pro 24H2 (Build 26100.1742) with an AMD Ryzen 9 7900X and 32GB DDR5 RAM.

Our test workload consisted of four concurrent Docker microservices (Node.js API, PostgreSQL 16, Redis 7, and Elasticsearch) running alongside VS Code Remote:

The results show a stark contrast. The default configuration hoards memory indefinitely. The 24H2 optimized configuration releases memory within seconds of build completion.

If your development containers also suffer from network disconnects or proxy drops, consult our walkthrough on WSL2 DNS and VPN connection repairs.

Frequently Asked Questions

Why is vmmemWSL taking up so much RAM?

The vmmemWSL process represents the lightweight Hyper-V virtual machine powering WSL2 and Docker Desktop. The Linux kernel caches files in RAM to speed up read operations. By default, Linux does not release this page cache back to Windows unless Windows experiences severe host memory pressure.

What is the difference between vmmem and vmmemWSL?

Windows 11 version 23H2 and 24H2 split the legacy vmmem.exe process into distinct binaries. The vmmemWSL.exe process handles Windows Subsystem for Linux distributions and Docker containers. The vmmemWSA.exe process handles the Windows Subsystem for Android.

Does wsl —shutdown delete my files or containers?

No. Running wsl --shutdown terminates active virtual machine processes and drops memory consumption to zero immediately. Your Linux files, container volumes, and installed packages remain safely stored on your virtual disk.

What does autoMemoryReclaim=dropcache do in Windows 11 24H2?

It tells the WSL2 virtualization layer to reclaim unneeded Linux page cache memory in real time. When Linux finishes a disk-heavy task like npm install or git checkout, WSL automatically returns that freed RAM to Windows without requiring a manual restart.

How do I shrink a bloated ext4.vhdx file?

Enable sparse mode in your .wslconfig file by adding sparse=true under [wsl2]. Then run wsl --manage <DistroName> --set-sparse true in PowerShell. This automatically shrinks the virtual disk as files are deleted.