Hidden Background Load After Windows 11 Updates: How to Check When Task Manager Looks Normal

Is Task Manager Really Closed?

How to Check Hidden Load After the Windows 11 KB5067036 Update

The optional Windows 11 preview update KB5067036 for versions 24H2 and 25H2 brings a redesigned Start menu and other improvements.

At the same time, some users and tech media have reported a strange side effect:

Task Manager appears to close, but it actually keeps running—or even duplicates itself—in the background, using CPU and RAM.

If your PC feels sluggish after installing KB5067036, even though Task Manager shows low usage, this guide will walk you through:

• How to check whether Task Manager is really closing
• How to detect “hidden” background load
• How to safely shut down extra Task Manager processes
• Additional checks for post-update performance issues
• When you might want to uninstall an optional preview update

1. What exactly is going on with KB5067036 and Task Manager?

KB5067036 is a non-security, optional preview update released in late October 2025 for Windows 11 24H2 and 25H2. It improves the Start menu, Windows Search and more.

Shortly after release, multiple outlets reported a bug where:

• Clicking the X to close Task Manager doesn’t fully terminate it.
• New Task Manager windows open while previous instances stay hidden but active.
• In extreme cases, dozens of Taskmgr.exe processes can accumulate and consume hundreds of MB of RAM.

Microsoft’s official KB page still lists “no known issues” for KB5067036, but reporters and users have documented the duplication bug and say Microsoft is working on a fix.

Because of this, it’s worth verifying whether Task Manager is truly closing on your system and checking for extra background load.

2. First check: Are you actually running KB5067036?

1. Open Settings (Win + I).
2. Go to Windows Update → Update history.
3. Under Quality updates (or Other updates), look for entries like:
   • “2025-10 Cumulative Update Preview for Windows 11 Version 24H2/25H2 (KB5067036)”.

If you don’t see KB5067036, you may be on another build and your issue could have a different cause.

3. Quick test: Does Task Manager really close?

Let’s run a simple experiment.

1. Press Ctrl + Shift + Esc to open Task Manager.
2. Switch to the Details tab.
3. Click the Name column to sort alphabetically.
4. Find Taskmgr.exe in the list and count how many entries you see.

Now:

5. Close Task Manager using the X in the corner.
6. Wait 5–10 seconds.
7. Press Ctrl + Shift + Esc again to reopen Task Manager.
8. Go back to Details and look for Taskmgr.exe again.

You should see exactly one Taskmgr.exe process each time.
If you see multiple entries, or the count keeps increasing every time you open Task Manager, you are very likely hitting the duplication bug described above.

Also watch the Performance and Processes tabs:

• Is Memory usage slowly climbing even when you do nothing?
• Do you see Task Manager itself using more RAM over time?

If yes, hidden Task Manager instances may be contributing to the load.

4. How to safely kill “immortal” Task Manager processes

If you discover multiple Task Manager processes, don’t worry—this is easy to clean up.

4.1 End all Task Manager instances from the command line

This is the most reliable method.

1. Press Win + X and choose Windows Terminal (Admin) or Command Prompt (Admin).
2. Run: taskkill /im taskmgr.exe /f
3. Wait a few seconds. All Task Manager windows will close, and any hidden background instances will be terminated.

You can then reopen Task Manager normally with Ctrl + Shift + Esc.

4.2 Use Task Manager to clean up itself

If you prefer to stay inside the GUI:

1. Open Task Manager.
2. Go to the Details tab.
3. Right-click each Taskmgr.exe entry and select End task (leave one if you don’t want to close the window you’re using).
4. Switch back to the Processes tab to confirm CPU and memory usage have dropped.

After this, repeat the quick test from section 3 to see whether the duplication reappears.

5. Checking for other “hidden” background load after an update

Even if you’re not affected by the Task Manager bug, Windows often performs heavy background work after large cumulative or feature updates:

• Windows Search indexer may rebuild its index, causing extra disk and CPU usage.
• Microsoft Defender Antivirus may run longer scans with fresh definitions, which can noticeably impact performance.

These activities are expected, but you can still check what’s going on.

5.1 Use Task Manager’s Performance view

1. Open Task Manager → Performance.
2. Click CPU, then right-click the graph and choose Change graph to → Logical processors.

Look for:

• A single core that is constantly high while others are low
  → often indicates a specific process stuck in a loop.
• Overall CPU low but Disk or Memory unusually high
  → can indicate indexing, antivirus scans or an app misbehaving.

5.2 Use Resource Monitor for disk and CPU details

1. Press Win + R, type resmon and press Enter.
2. Check the CPU and Disk tabs.

Common culprits after updates include:

• SearchIndexer.exe (Windows Search)
• MsMpEng.exe (Microsoft Defender)
• explorer.exe or ShellExperienceHost.exe (shell / UI)
• Third-party utilities that hook into the shell or taskbar

If one of these processes shows constant activity, give the system 30–60 minutes of idle time to finish its work. If the load never subsides, you may need more targeted troubleshooting.

6. Advanced tools if your PC still feels slow

If performance remains poor long after the update and reboot, you can dig deeper.

6.1 Reliability Monitor

1. Open Start and search for “Reliability Monitor”.
2. Open View reliability history.

Look for:

• Red X or warning icons around the date when you installed KB5067036.
• Repeated failures for shell components (e.g. ShellExperienceHost.exe, StartMenuExperienceHost.exe) or drivers.

This can hint at crashes or repeated restarts that contribute to sluggishness.

6.2 Event Viewer

1. Right-click Start → Event Viewer.
2. Under Windows Logs → System, filter by Error and Warning.

If you see the same component logging errors repeatedly during normal use, that module may be misbehaving after the update.

6.3 Performance Monitor

For power users:

1. Press Win + R, type perfmon and press Enter.
2. Add counters like Process → % Processor Time, Disk → Disk Transfers/sec for specific processes.

This lets you watch exactly how much CPU and disk individual processes use over time.

7. Should you uninstall KB5067036?

Because KB5067036 is an optional preview update, you don’t have to keep it if it causes trouble.

7.1 When it makes sense to uninstall

Consider rolling back if:

• Task Manager duplication keeps returning.
• Your system is noticeably slower only after this update.
• You depend on a stable machine for work and can’t wait for a fix.

7.2 How to uninstall KB5067036

1. Open Settings → Windows Update → Update history.
2. Scroll down and click Uninstall updates.
3. Look for KB5067036, select it, and choose Uninstall.
4. Restart your PC when prompted.

After uninstalling:

• Windows will return to the previous cumulative update.
• You can skip KB5067036 in the future until Microsoft publishes a fix or it’s superseded by a newer, stable update.

8. Best practices for future Windows updates

To avoid surprises like this in the future, a few habits can help:

1. Treat preview updates as optional on production PCs.
   Install them only if you need a specific fix or feature.
2. Create a restore point or backup before major updates.
   System images or third-party backup tools make it easy to roll back if something goes wrong.
3. Limit startup apps and background utilities.
   Fewer always-on tools mean fewer conflicts when Windows internals change.
4. Give Windows some idle time after big updates.
   Let it finish indexing, optimizing, and scanning before judging performance.

9. Summary

• KB5067036 is an optional Windows 11 preview update that adds a new Start menu and other improvements for 24H2/25H2.
• Some users have reported a Task Manager bug where the app doesn’t fully close and can even duplicate itself, causing hidden CPU and memory usage.
• You can check for extra Taskmgr.exe processes on the Details tab, and clean them up with taskkill /im taskmgr.exe /f or by ending them manually.
• After any major update, Windows may also perform heavy background tasks (indexing, antivirus scans), which can temporarily slow your PC.
• If problems persist and clearly started with KB5067036, you can uninstall this preview update and wait for a future, stable release.

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タグ: Windows 11, Windows Performance, Windows Update Issues, Task Manager, KB5067036, Performance problems, Background processes