Published Mar 15, 2026, 8:00 AM EDT
Afam's experience in tech publishing dates back to 2018, when he worked for Make Tech Easier. Over the years, he has built a reputation for publishing high-quality guides, reviews, tips, and explainer articles, covering Windows, Linux, and open source tools. His work has been featured on top websites, including Technical Ustad, Windows Report, Guiding Tech, Alphr, and Next of Windows.
He holds a first degree in Computer Science and is a strong advocate for data privacy and security, with several tips, videos, and tutorials on the subject published on the Fuzo Tech YouTube channel.
When he is not working, he loves to spend time with his family, cycling, or tending to his garden.
It's not surprising when your computer's SSD fills up after prolonged use. However, when it happened to me last week, it came as a shock because I hadn't recently downloaded or installed any large files.
So, out of habit, I emptied my Recycle Bin and other commonly used folders like Downloads and even my temporary files. Unfortunately, these actions made almost no impact. I then ran a scan using one of my favorite disk analyzers and, for the first time, I started to get a picture of what was actually happening. Certain Windows folders that I rarely look at had grown very large. I learned what the common culprits are and why.
WinSxS
Windows' Component Store
The WinSxS folder found in C:\Windows\WinSxS stands out among system files when you sort by size. On my system, it was 16.3GB, but generally it ranges between 15 and 25GB and may seem like an obvious destination for manual cleanup. But this folder is the Windows Component Store.
It's where the system stores updated components after the OS installs new updates. As new versions of system files are added, this folder will grow. The older versions that remain serve three important functions:
- Uninstall problematic updates
- Repair corrupted system files
- Maintain compatibility between components
However, because several files in this folder are hard-linked to other Windows locations and Explorer counts them multiple times, the actual size of WinSxS is exaggerated. So even though this folder is growing, it's not actually as large as it looks. But it still needs cleanup. The safe way to reduce the footprint is to run the DISM command below with elevated rights:
DISM /Online /Cleanup-Image /StartComponentCleanup
After running this command, the folder went from 16.3GB to 11.8GB.
You can take a more aggressive approach to cleanup by running the command below, but note that using /ResetBase prevents rollback to earlier updates and may complicate troubleshooting.
DISM /Online /Cleanup-Image /StartComponentCleanup /ResetBase
Never manually delete files in the WinSxS folder to avoid breaking Windows updates or, in some cases, making the computer unbootable.
AppData
The hidden user folder where apps stockpile gigabytes
AppData is another storage hog on Windows. It's located in the path: C:\Users\[YourName]\AppData. This folder can very easily go unnoticed on Windows because it is hidden by default. The AppData folder has the following three subfolders:
- Local: temporary files and application caches
- LocalLow: data used by sandboxed or restricted apps
- Roaming: settings that follow your account across devices in domain environments
The Local folder typically holds the most storage bloat of the three. But generally, the bloat in AppData arises from large caches, log files, and update packages of modern apps. Electron apps are a major contributor to the bloat. These are apps like Discord, Spotify, and Microsoft Teams that are built using a bundled Chromium browser engine.
Your browsers also add a lot of bloat to the AppData folder. It's the location where Chrome, Edge, and Firefox store caches, extensions, and profile data. My AppData folder was 140GB in size. Browsers were one of the biggest culprits, and after deleting several profiles I no longer use, removing leftover app folders, and clearing other cache data, I recovered about 25GB.
You can manually clear a lot of its folders, especially the ones labeled Cache, Temp, or GPUCache. But don't delete entire application folders for apps that are still installed.
Windows upgrade leftovers
The folders Windows forgets after major updates
When you undergo a major Windows upgrade, the process is more similar to an operating system migration than a simple patch. Windows maintains a copy of the old installation just in case something goes wrong, and you need to revert to it. This backup is stored in the path C:\Windows.old. This directory can be anything between 10 and 35GB. On my system, it was a 32.7GB folder.
The Windows.old folder serves only as a rollback option that is relevant for 10 days on Windows 11 and 30 days on Windows 10 after the upgrade. These are all the possible folders you may have after a major upgrade:
Folder
What it contains
Safe to delete
How to remove
Windows.old
Previous Windows installation
Yes (after upgrade period)
Disk Cleanup or Storage settings
$WINDOWS.~BT
Windows upgrade installation files
Yes
Disk Cleanup
$WINDOWS.~WS
Setup and upgrade staging files
Yes
Disk Cleanup
Most of the time, Windows.old is automatically deleted after the rollback period elapses. However, in some cases, especially when the upgrade process has been interrupted or there is a problem with cleanup tasks, it may remain indefinitely. This will require manual cleanup.
Virtual disks and build caches that expand but rarely shrink
Developer tools introduce new sources of storage usage that can grow quickly. With WSL (Windows Subsystem for Linux), every Linux distribution has a .vhdx extension and runs inside a virtual disk file. However, the problem is that even after files are deleted, the virtual disk (.vhdx file) does not shrink automatically.
It's a similar case with Docker, where over time you can easily accumulate containers, images, and volumes. With certain developer tools, you may also have multiple versions of runtimes and SDKs simultaneously installed. Below are the storage locations you must keep an eye on:
Tool
Storage location
Why it grows
Cleanup method
WSL
C:\Users\[Username]\AppData\Local\Packages\[distro-name]\LocalState\ext4.vhdx
Disk expands but doesn't shrink
Compact the disk manually
Docker
C:\Users\[Username]\AppData\Local\Docker\wsl
Containers accumulate
docker system prune
npm
C:\Users\[Username]\AppData\Local\npm-cache
Package downloads
npm cache clean --force
SoftwareDistribution
Windows Update cache
Within the Windows directory, there is another folder that is constantly growing. It's the staging area for Windows updates and can be found in the path: C:\Windows\SoftwareDistribution\Download. Before update packages are installed, they are downloaded to this location.
Windows may remove the update packages, but from my experience, it's not always a guarantee. If left unchecked, it may grow to be multiple gigabytes of leftovers. However, to clean safely, you must run the three commands below in sequence. They stop the Windows Update service, delete the Download folder's content, and restart the Windows Update service again:
net stop wuauserv
rd /s /q "C:\Windows\SoftwareDistribution\Download"
net start wuauserv
net start bits
The rd command removes the folder and its contents. You should only run it when Windows Update is not actively installing updates or waiting for a restart. If not, certain files will not be deleted. Some experts have reported that the SoftwareDistribution folder may grow as much as 15GB.
Tools and habits that prevent storage bloat
The most significant lesson for me was that it's very easy to miss the real culprits. One of the things that helped the most was using disk analyzers to visualize storage use. Any of the tools below will be helpful:
Tool
Speed
Strength
WizTree
Extremely fast
Scans large drives in seconds
TreeSize Free
Balanced
Clear folder navigation
WinDirStat
Slower
Detailed visual map
I also keep a stack of maintenance tools handy because daily use often triggers small system problems.