Windows Update May Solve High CPU Usage Bug

John Lister's picture

Microsoft has released an optional Windows 10 update that could solve a recent problem with high CPU usage. Users who haven't had this problem can probably give the update a miss.

The update, with the reference KB5001391 is optional as it's a "C release". That means it's made up of fixes and features that will roll out in the main update cycle later on but are available now as a preview.

The main point of interest in KB5001391 is a fix for a memory problem. Microsoft hasn't made things entirely clear but it appears it's targeted at recent reports of users suddenly seeing their CPU usage rocket to the point that their computer slows down or even becomes unresponsive. (Source:

Race Condition Problematic

It seems to be a "race condition" problem. With Windows, that's to do with the way computer processors organize their equivalent of a to-do list into different threads. Each is a set of instructions in order of completion, with each thread corresponding to a particular application or task.

A race condition arises when two threads need to access the same piece of data and one or both threads involves changing that data. That can mean one thread running into problems because the data changes unexpectedly mid-process. In the worst case scenario it can create a loop with two threads changing the data back and forth endlessly.

Users who've experienced the CPU problem can try the update by opening Windows Update in their Windows settings, then looking for KB5001391 in the "Optional quality update" section. It may require a click on "Check for updates" to make it appear. (Source:

Update Still In Test Stage

For most other users there's no real benefit installing the update. It doesn't contain any security fixes and the main addition is a "News and Interests" section in the Windows taskbar.

These optional "C" updates are effectively a way for Microsoft to test fixes and updates on real world machines without having to deal with the headache of something going wrong on tens of millions of computers when the regular update rolls out.

What's Your Opinion?

Have you experienced the CPU problem recently? Do you ever install manual, optional updates? Should Microsoft be clearer about the potential problems with these preview updates?

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