Windows 11 slow after an update: what to do

Windows 11 running slowly right after an update is usually a temporary slowdown: Windows is finishing, in the background, the work started by the update. It's worth worrying about if the slowness lasts several days, and in that case the causes can be checked one by one.

1. Leave the computer on and plugged in for 30 to 60 minutes, without putting it to sleep.
2. Choose 'Restart', not 'Shut down'.
3. Install any remaining updates in Windows Update: a fix often follows a problematic update.
4. If the slowness lasts more than a few days, follow the step-by-step method below.

Windows 11 gets two kinds of updates. Cumulative updates, released every month (on the second Tuesday), fix security holes and bugs: they install quickly and rarely slow the computer for more than a few hours. Feature updates, once a year (for example 24H2 then 25H2), reinstall a large part of the system: slowdowns after them are the most common and the longest. To see which one you received, open Settings > Windows Update > Update history.

1. Post-update work

Once the update is installed, Windows still has work to do: finalising components (TiWorker, TrustedInstaller), optimising program libraries, re-indexing your files for search (SearchIndexer) and running a new antivirus scan (MsMpEng). For 30 minutes to a few hours, the processor and disk are very busy. On a PC with a mechanical hard drive, this phase can last a whole day.

2. A restart that didn't really happen

Some updates are only complete after a real restart. But with Windows fast startup, 'Shut down' then powering on again is not a full restart. The update stays half-applied, and the computer can remain slow until you choose 'Restart'.

3. A replaced driver

An update can replace the graphics, Wi-Fi or disk driver with a generic version. The result: choppy display, slow network, or a computer that lags in a new way. Update history shows whether a driver was changed.

4. New startup programs

Updates to Windows or other software sometimes add items that launch at startup. They weigh down power-on without you installing anything.

5. A suddenly nearly full drive

After a feature update, Windows keeps the previous version in a 'Windows.old' folder, often 15 to 30 GB, so you can roll back. On a small drive, that's enough to drop below 10% free space, and everything slows down.

6. Settings reset

A big update can re-enable features you had turned off (startup apps, sync, visual effects) or change the power mode. A computer switched to an energy-saving mode feels noticeably slower.

7. Damaged system files

More rarely, an interrupted update (power cut, computer switched off mid-install) leaves Windows files damaged. The symptoms are then confusing: slowness, windows that no longer open, updates failing in a loop.

Open Task Manager (Ctrl + Shift + Esc) and sort processes by 'CPU' then by 'Disk'. If you see TiWorker, TrustedInstaller, SearchIndexer, MsMpEng or 'Windows Update service' at the top, Windows is finishing its work: be patient. If those names are gone and the computer is still slow, the cause lies elsewhere.

1. Leave the computer on and plugged in for 30 to 60 minutes, without putting it to sleep, so Windows can finish its work.
2. Choose 'Restart' (not 'Shut down') from the Start menu.
3. In Settings > Windows Update, install any remaining updates: a fix often follows a problematic update.
4. Check the power mode: Settings > System > Power (or 'Power & battery'), set to 'Balanced' or 'Best performance'.
5. Check free space: Settings > System > Storage > Temporary files. Once you're sure everything works, 'Previous Windows installation(s)' frees the space used by Windows.old.
6. In Settings > Windows Update > Update history, check whether a driver was updated. If so, install the version from your computer or graphics card manufacturer's website.
7. If the slowness started with a specific update and has lasted several days, the same page offers 'Uninstall updates'.
8. After a feature update, Settings > System > Recovery > 'Go back' returns to the previous version for 10 days.
9. As a last resort, Windows' built-in repair fixes damaged system files: in a terminal opened as administrator, type DISM /Online /Cleanup-Image /RestoreHealth, then sfc /scannow. On recent Windows 11, Settings > System > Recovery also offers 'Fix problems using Windows Update', which reinstalls Windows while keeping your files and apps.

A slow update is not a reason to replace your computer: in the vast majority of cases, everything goes back to normal within a few hours or after a real restart.

• Run updates when you don't need the computer, for example in the evening, plugged into mains power.
• Never switch it off during installation, even if it seems stuck: that's how system files get damaged.
• Keep at least 20 to 30 GB free before a feature update.
• Windows Update lets you pause updates one week at a time, up to five weeks: handy before a busy period. Don't block them longer, they fix security holes.

• The same update fails and reinstalls at every startup.
• Windows shows 'Preparing Automatic Repair' in a loop, or a black screen after signing in.
• The slowness lasts more than a week despite the steps above: the cause is probably not the update itself, but a problem it revealed (a tired drive, not enough memory).

Nyctale recognises Windows tasks working in the background (update installation, antivirus scan, indexing) and simply tells you to wait when that's the case. It also checks whether the computer has truly restarted, counts startup programs, checks free space and, when run as administrator, the integrity of Windows files.

If, after an update, you get crashes rather than slowness, see our guide to the Windows 11 blue screen. To measure precisely what slows the machine, see the free PC diagnostic tools.