Fix Slow PC After Windows Update

Computer running slow after a Windows update? Don't panic. Here's why it happens and what to do, from background tasks to system file repair.

Published 2026-02-04 by TechNet New England

Your computer was running fine yesterday, but after installing a Windows update, everything is painfully slow. Programs take forever to open, the Start menu lags, and even clicking around on the desktop feels sluggish. Before you assume something is broken, there are a few things to understand and try.

Why Updates Slow Down Your PC (Temporarily)

Right after a major Windows update, your computer runs several background processes that can temporarily affect performance:

In many cases, the slowness resolves on its own within a few hours. If your PC is still slow after a day, it's time to take action.

Fix 1: Restart Your Computer (Yes, Really)

A Windows update often requires more than one restart to fully complete. Even if your PC restarted during the update installation, some components may still be finalizing in the background. Do a fresh restart:

  1. Click Start > Power > Restart
  2. Use "Restart," not "Shut down." Shut down with Fast Startup enabled doesn't fully reset the system the way Restart does
  3. After the restart, give the PC a few minutes to settle before judging performance

Fix 2: Check Task Manager for Resource Hogs

  1. Press Ctrl+Shift+Esc to open Task Manager
  2. Click "More details" if it opens in compact mode
  3. Click the CPU column header to sort by CPU usage, then check Disk and Memory too
  4. Look for processes consuming unusually high resources

Common post-update resource hogs include:

If a specific third-party program is using all the resources, it may need to be updated to be compatible with the new Windows version.

Fix 3: Run the System File Checker

Sometimes an update doesn't install cleanly and leaves corrupted system files. The System File Checker (SFC) scans for and repairs these:

  1. Open Terminal or Command Prompt as administrator
  2. Run the following command:

sfc /scannow

  1. Wait for the scan to complete (it can take 10-15 minutes)
  2. If it finds and repairs files, restart your PC

If SFC reports issues it couldn't fix, follow it up with a DISM repair:

DISM /Online /Cleanup-Image /RestoreHealth

This command downloads fresh copies of any damaged system files from Microsoft. It requires an internet connection and can take 15-30 minutes. After it completes, run sfc /scannow one more time, then restart.

Fix 4: Check for Additional Updates

Sometimes a problematic update is quickly followed by a fix:

  1. Go to Settings > Windows Update
  2. Click "Check for updates"
  3. Install any available updates, including optional updates
  4. Also check for driver updates: Click "Advanced options" > "Optional updates" and look for driver updates

Fix 5: Uninstall the Problematic Update

If the slowness started immediately after a specific update and nothing else helps, you can remove it:

  1. Go to Settings > Windows Update > Update history
  2. Click "Uninstall updates"
  3. Find the most recent update, click on it, and select "Uninstall"
  4. Restart your computer

After uninstalling, you can pause updates for a few weeks from Settings > Windows Update to give Microsoft time to release a fixed version.

Fix 6: Clean Up Disk Space

Updates can leave behind temporary files that take up space and slow things down:

  1. Open Settings > System > Storage
  2. Click "Temporary files"
  3. Check the boxes for "Windows Update Cleanup," "Temporary files," and "Delivery Optimization Files"
  4. Click "Remove files"

If these steps don't resolve the issue, or if you'd like professional help, our team is here. Contact TechNet New England for IT support.