Windows’ System Process was Killing my CPU. An update may have been to blame.

tl;dr I uninstalled KB4022725.

About a week ago I received a new monitor in the mail; a 34-inch, Ultra-Wide, 21:9 Curved LG. Like a kid on Christmas I tore through the box, and elevated the new display to my desk with the type of caution and reverence Indiana Jones would use when lifting a rare jewel from an ancient cave.

Me and my monitor were inseparable, for about a day. You see, it was around this time that I started noticing my computer would lock-up for a couple of seconds. The lock-up affected not only the mouse’s ability to traverse my new sea of pixels, it also affected my ability to video-chat with co-workers, and even use my Bluetooth headphones. I was ruined.

After a few days of this, I decided I should start reducing the complexity of my system. I use a Surface Book i7, an external Dell monitor, my new LG, a wireless Microsoft Mouse and Keyboard, and the official Surface Dock. I immediately removed the Dell monitor, and the Surface Dock, but the problem remained.

As is typical, I wound up doing what I should have done from the start, and opened Task Manager to see what was going on, and what could be done.

Task Manager showing System process using 29.6% CPU

I sat in amazement; the System process was bouncing between 25% and 35%. At times, it would go even higher than that.

Had this been some tertiary process on the machine, I would have just killed it. That approach clearly wouldn’t work with this process. I would have to dig a bit further, and identify what about the System process needed so much CPU.

To peel back System’s exterior, I downloaded Mark Russinovich’s Process Explorer. (Many of you are familiar with Mark, no doubt. But if you’re not, be sure to bookmark his Sysinternals Suite page.) Within a couple of minutes, I had more information.

Process Explorer showing CPU allocated to ntoskrnl.exe!KeIsAttachedProcess

While I had more information, there wasn’t much I could do with it. Searching the web turned up similar CPU/RAM issues for other users, but nothing that matched my scenario. I resolved to Tweet in anguish, and leave it at that. I wondered if perhaps leaving the machine alone for 12 hours would let the issue run its course. I was wrong.

I woke up this morning thinking that this could only be explained by something wrong in Windows. After all, the problem didn’t even require me to log in — the mere act of turning on my PC caused my fan to go berserk after a few seconds.

The way I see it, I was faced with 2 options: 1) Reset/reinstall Windows, 2) Identify what change could have caused the new behavior. Given I work a day job, and need my computer, I decided to take Option 2 and scan my recent updates for answers.

In the past week, I’ve had a few updates. Might as well uninstall the most recent, and see what happens. First up, KB4022725. Microsoft claims this updated aimed to improve quality. We’ll see about that!

I uninstalled, restarted, allowed Windows to complete its update process, and sat in silence as the machine crept closer and closer to the horizon of my pain.

Then, in an instant, there was silence. The voice of my children could be heard from down the hall. Branches blowing in the wind sang a gentle chorus outside my window. The air was filled with all sorts of sounds. Noticeably absent from the congregation of sounds, my PC fan.

I opened Task Manager again to take a closer look.

Task Manager showing System process using roughly 0.9 to 1.6% CPU

Was that it? That’s all that needed to be done? Had Microsoft really released an update for their top of the line hardware without thoroughly testing? So many questions. But I was too busy to ask them; I just wanted to get to work.

I hate that I had to uninstall an update. You’ll find no bigger advocate for aggressively applying updates than me. I manually check many times a week for updates, and apply any and all that are found. My wife swears that I’m making our computers slower; I’ve passionately argued to the contrary. Then again, maybe she’s right.