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Windows 7: Intermittent 100% CPU load, slow down, can't find the cause

26 Sep 2018   #1

Win 7 Pro 64 bit
Intermittent 100% CPU load, slow down, can't find the cause


Periodically (maybe every 5-15 minutes) the CPU usage in the Task Manager Performance tab shoots up to 100% and the machine slows to a crawl. If I'm watching a video or a video conference it freezes, or at least the audio breaks up badly.

The CPU column under Processes doesn't give much of a clue - the process at the top of the list when it happens could be a variety of different ones. Also, using Process Hacker to look at CPU usage doesn't really help - the top process when it happens could be Chrome, System Idle Process, Process Hacker or just about anything else.

I reinstalled Windows and it was OK for a while (I think) but then it started happening again. However, this may have been after I started re-installing drivers and/or programs (but I still haven't found a rogue program).

I have run Avast anti-virus and Malwarebytes, with no result. Should I scan for a root kit with some other tool?

This is driving me a bit crazy - all suggestions welcome.

Melbourne, Aus

Lenovo X201t
Win 7 Pro 64 bit
i5 2.67 GHz

Attached Thumbnails
Intermittent 100% CPU load, slow down, can't find the cause-2018-09-26-21_46_49-process-hacker-x201t_pp-.png  
My System SpecsSystem Spec
26 Sep 2018   #2

Win 10 x64, Linux Lite, Win 7 x64, BlackArch, & Kali

Hi pmhutch,
Welcome to SevenForums!
It's most likely Windows Update, if you have it set to check for updates. How do you have it configured?
This is an excellent tool to view what's using CPU cycles!
Windows Directory Statistics WinDirStat

I would temporarily set Win Update to Never check for updates, if your issue stops, that's the culprit!
My System SpecsSystem Spec
26 Sep 2018   #3

Windows 7 HP 64

Welcome to the Forum.

I agree with @Snick. Can be WU.
I've once faced a delay as described.
It wasn't an update file. It was the SEARCH for update that was running forever and kept the computer so busy that was causing the delays.
So I set, under services, WU to manual and on WU page to never check and the problem has gone.

Run WU manually. Does it search forever?

Is your Malwarebytes free or paid?
My System SpecsSystem Spec

26 Sep 2018   #4

Win 10 x64, Linux Lite, Win 7 x64, BlackArch, & Kali

Agree with @Megahertz07.
WU latest engine update was supposed to address this "SEARCH for update", yea, supposed to.
My System SpecsSystem Spec
27 Sep 2018   #5

Win 7 Pro 64 bit

Hi there

Thanks for the replies.

I set Windows Update to "Never check for updates" and got quite hopeful as the problem seemed to have stopped. However, after about 10 minutes it started again

I was in a Zoom video conference for about an hour and it gave a good opportunity to see the problem in action. See attached screen shot.

For much of the time, things were fine - CPU load at a reasonable level in Windows Task Manager (32% in the screen shot), top of the CPU column in Process Hacker was System Idle Process, at 66.76, Zoom.exe at position no. 2 with CPU = 10.56, everything working fine.

Then, every few minutes, the CPU Usage in Task Manager would go to 100%, Zoom.exe would go to the top of the list with CPU = 50 to 60 in Process Hacker and System Idle Process would have disappeared from the list (or dropped down the list - not sure, but not at the top any more). The fan on the PC speeded up and the audio in the Zoom conference started to break up and Zoom gave a warning message about "Low System Resources". After a minute or two, things would go back to normal, with System Idles Process at the top of the list and Zoom.exe at #2 with a reasonable (much lower) CPU figure in Process Hacker.

I have subsequently noticed this with other tasks instead of Zoom e.g Chrome: Windows Task Manager CPU goes to 100%, Chrome.exe goes to the top of the list with a high (50+) CPU figure in Process Hacker and everything slows down or grinds to a halt (to the extent that I can't use Greenshot to take a screenshot in this condition - cursor movement is very sluggish and erratic). Then after a minute or two things go back to normal.

So, it looks like something in the OS may be boosting the priority or CPU allocation of a legitimate task to an excessive degree such that it hogs resources for a while, then it sorts itself out. Very annoying.

Any further ideas welcome.


PS I am using the free version of Malwarebytes. Would the paid version be better for trying to find and fix the problem (hope it's available on a free trial...) I don't know much about "root kits" - could one of these be to blame, and how would I find out?

Attached Thumbnails
Intermittent 100% CPU load, slow down, can't find the cause-process-hacker-2.png  
My System SpecsSystem Spec
27 Sep 2018   #6

Windows 7 HP 64

I've asked about Malwarebytes version because the paid version is active all times and should be considered a antvirus replacement. I don't like programs that are loaded on startup and remains in memory even when not in use. That is the case of Chrome and Malwarebytes free.

You can use msconfig to disable all startup programs (leave only MS services). If the problem is over, enable half. Proceed till you find the one is causing the problem.
My System SpecsSystem Spec
27 Sep 2018   #7

Win 10 x64, Linux Lite, Win 7 x64, BlackArch, & Kali

I agree with Megahertz07!

I have most startup programs disabled, done from CCleaner > Tools > Startup with the exception of Windows/Microsoft system programs, updaters, Anti-virus or similar.

Malwarebytes Premium or Free utilizes the same search engine and definitions. The advantage of Premium is that it is Real-Time protection & compatible with & an excellent supplement to other Anti-virus programs.

I don't like Chrome (not installed), Edge, or Internet Explorer. I prefer Firefox Quantum, like the customization options, and about:config tweak-ability
My System SpecsSystem Spec
27 Sep 2018   #8
F22 Simpilot

Windows 7 Ultimate x64

Run Autoruns, post the ARN file. You will need to zip it.

What is zoom? What is that downloader process? Zoom.exe looks to be some form of so-called "PC booster."
My System SpecsSystem Spec
27 Sep 2018   #9

Win 10 x64, Linux Lite, Win 7 x64, BlackArch, & Kali

Zoom: Video Conferencing, Web Conferencing, Webinars, Screen ...

Zoom above is similar to TeamViewer

Zoom.exe is also a virus, and not the same as above linked ZOOM

Downloaded process is RealDownloader is a freemium download manager by RealNetworks that downloads embedded Internet videos in multiple formats including MOV and FLV from sites such as YouTube, CollegeHumor, Facebook, Funny or Die and Dailymotion. This software utility lets users share downloaded videos on social networks and transfer them to their mobile devices.

My System SpecsSystem Spec
30 Sep 2018   #10

Win 7 Pro 64 bit

Hello again

Zoom.exe is the client software for Video Conferencing, Web Conferencing, Webinars, Screen Sharing - Zoom, a video conferencing service which I was using at the time that I took the screen shot (not a virus in this case). It goes away when I exit the application.

Have run Autoruns - .arn file is attached (as a Zip - actually I'm a bit surprised at the difference in file size : 7.5 megs as .arn, 253 kb as a Zip - is that simply because there's a lot of blank space in the .arn which can be compressed?)

I'm quite amazed at the number of items in the Autoruns result!

I'm going to go and cut back on the Autorun / Auto start programs using Ccleaner, as suggested above. I'm wondering whether pruning the Services might also help? Given that there is nothing visible in Task Manager which is causing this (i.e no visible task) is it more likely that it is a Service?

Thanks for all the on-going help and advice.

Attached Files
File Type: zip X201t Autoruns (252.1 KB, 2 views)
My System SpecsSystem Spec

 Intermittent 100% CPU load, slow down, can't find the cause

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