Windows 11 KB5041872/KB5038603 downloads get stuck at 8% with 100% CPU, PC lag, slowdown

A broken Windows 11 logo indicating bugs

A bug or an issue in the Windows 11 Dev channel should not raise too many eyebrows as it is an Insider channel meant for testing. However, one issue that pops up from time to time that Microsoft seemingly has not been able to fix is the update download bug wherein a new Windows update fails to download smoothly as it gets stuck in the pipeline.

Neowin noticed that such a bug has sprung up in the Dev channel with the latest build, 26120.1542, released under KB5041872. Affected users are reporting that their download progress gets stuck at 8%, while some add that their system's CPU usage gets pegged at 100%. Clearly, the download process is trying to do something in the background, leading to such high cycles. This is leading to system slowdown, lagging, and freezing.

Microsoft forum user Sujal Thakkar [BCA - 2023] has posted about the issue inquiring about possible ways to work around the problem. The question has been upvoted by 49 others at the time of writing. They wrote:

I am trying to update the build Cumulative Update for Windows 11 Insider Preview (10.0.26120.1542) (KB5041872).

However, whenever I attempt to download the update, it consistently gets stuck at 8%. When it reaches 8%, the CPU usage by the Windows Modules Installer spikes to 80-90%, causing the PC to become unresponsive and slow. The issue resolves after restarting the PC and pausing the update. However, the problem reappears as soon as I resume the update, making it difficult to use the PC smoothly. I have tried restarting the Windows Modules Installer and Windows update from the systems. But it still is not resolving.

Another user on the forum, matGV, also has a query about a similar issue affecting KB5038603, an earlier build. The issue has been upvoted by 24 others at the time of writing.

Added details in their post suggest that the high CPU usage is the result of TiWorker EXE which is short for Windows Update Trusted Installer Worker Process. They add:

I am experiencing an issue with the Cumulative Update for Windows 11 Insider Preview (10.0.26120.1252) (KB5038603). The download remains stuck at 8% and does not progress. Here are some additional details about my system and what I have tried so far:

Windows Version: Windows 11 Insider Preview

Build Number: 10.0.26120.1252

Update Type: KB5038603

...

Additionally, I have noticed that the TiWorker.exe process is using a high amount of CPU, which significantly slows down my system. This also causes frequent crashes in games and applications.

An issue on the Feedback Hub has been raised as well by user Judge L, who wrote: