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Windows Modules Installer Worker using high CPU

This is Windows Update installing or cleaning up updates. Let it finish, restart, and it goes quiet.

Published October 13, 2026. Steps are for Windows 11 and 10.

What it is

Windows Modules Installer Worker is TiWorker.exe, the part of Windows Update that installs updates and Windows features and removes old versions of system files afterwards. It's busiest right after updates download, before and after a restart, and during automatic maintenance.

On a PC with a hard drive instead of an SSD it can keep the disk at 100% for half an hour or more.

Is it safe to end?

Don't. Stopping it in the middle can leave an update half-installed, and Windows starts it again anyway.

Let it finish, then restart

  1. Open Settings → Windows Update and see whether an update is installing or waiting for a restart.
  2. Leave the PC on until it's done, then restart if asked.

To stop updates from restarting your PC while you work, set Active hours in Settings → Windows Update → Advanced options.

If it's busy for hours, every day

An update that keeps failing will reinstall over and over. First run the troubleshooter: on Windows 11, Settings → System → Troubleshoot → Other troubleshooters → Windows Update. If that doesn't help, repair Windows' system files. Open Terminal as administrator and run these one after the other:

DISM /Online /Cleanup-Image /RestoreHealth
sfc /scannow

Both take a while. Restart afterwards and check Windows Update again.

See it live on your PCKnow My PC recognises Windows Update when it's the cause and tells you it will finish on its own, so you don't end it by mistake.
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