Windows Defender scan very slow. @ AskWoody (2024)

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“Desktop is from June 2013 : i5-3470CPU : 3.20 GHz : 8.00 GB RAM
Laptop is from Sept 2016 : AMD A8-8600P : 10 cores 4C + 6G : 1.60GHz : 4.00 GB RAM
The desktop has double the CPU speed and double the RAM.
— Also what size HDD’s are there on each PC?

Those could be factors
“CPU up to 100% at times : Mem 64% : Disk up to 100% at times.”
— I imagine that pertains to your slower laptop?

“Laptop has Lenovo Recovery (Q) Drive showing in ‘My Computer’ window with size of 13.8 GB.
“Properties” show the drive as empty though !! Can it be involved in any slowness ?”
— I’m not sure about that yet.

“Disk Clean-up shows 7.97 GB available ( 6.5 GB is Windows Update Clean-up). Haven’t done this yet – do you think it necessary?”
— I do clean that up when I see that in order save as much disk space as possible.

“Don’t know if Defender is doing Auto Daily Quick scan. How would I check ?”
Click on the hidden icons on the taskbar right side.
Click on the Windows Defender icon. It should have a white arrow within a green background.
— If yours have different colors let us know.
The security at a glance dashboard will show up
Most entries should have the white arrow within a green background.
— If yours have different colors let us know.
Open virus and threat protection
— It will report information for it’s latest Quick scan
— It runs automatically every day for me but not at the same time everyday.

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100% disk and CPU is unusual. Check your disk for problems with the disk manufacturers diags.

Make a backup first, as always.

cheers, Paul

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Let’s go over “The laptop has 386 GB free out of 451 GB so is it still necessary to clean up ? Will the 7.97 GB cause such a huge slowdown on the scan ?” in your post #2251919.
I treat my PC’s like I treat my car, house etc.: keep them well maintained even if there isn’t an issue yet.
I deal with items like that as part of my monthly maintenance regimen.
— It’s not something I look for unless there’s an outstanding issue similar to your situation: I just let it be taken care of during my monthly maintenance regimen.
— At this point in time it may not be a major issue but don’t wait until eventually things get worse.
— You’ve only had your Windows 10 on this laptop since January 2020.
— Keep it well maintained while its easy to do.

On Windows Defender, I’m notified by Notifications every day when it has run.
— That can be adjusted or turned off I believe but I don’t have a problem with being notified as I make sure my security protection is well maintained similar to my monthly maintenance regimen.
— Plus with the PC’s I work on, too many of them are all of a sudden infected and I show those whom I help how to make sure their AV keeps their PC safe & secure regardless of which AV they use.

It shouldn’t be necessary to run Windows Defender Full Scan: let it run Quick Scan for the days/time your laptop is in use.
— As has been requested, do you have another anti-virus or other security software installed?

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That’s great daddybear that you want to stay on top of how your PC’s run.
— I remember doing a “housekeeping” procedure on a weekly basis once upon a time, moved up to bi-weekly and became confident in going with a monthly schedule.

On your Windows Defender Quick and Full scans every two weeks, may I recommend allowing Windows Defender to run automatically on a daily basis and replace the full scan with Windows Defender Offline scan only once a month?
— I don’t think it makes sense to run the full scan as it takes as long as 2 hours 40 minutes.
— Your Windows Defender dashboard looks fine.

You could still troubleshoot the full scan concerns you have brought up
— The factors on that are there are twice as many files compared to your desktop PC but after researching that myself recently that doesn’t seem unusual for whatever reason.
— BTW I don’t think this has been asked about: do you use more “intensive” apps, games or demanding items that take up system resources on the laptop?
Now onto the speed: the 500 GB 5400 rpm HDD is a factor vs. the 1 TB 7200 rpm HDD.
— Would you consider an SSD or a 7200 rpm HDD?

On the “Have seen very heavy CPU usage during scan of a process called MsMpEng.exe – do you think this could be involved in slowing down the scan?”
b has explained what that is.
I don’t believe it’s a cause of slowing down the scan but it’s a result of the factors that have been mentioned.

I’d like to get back to “BTW I don’t think this has been asked about: do you more “intensive” apps, games or demanding items that take up system resources on the laptop?” relative to system resources.

Use Windows PowerShell (Admin) or Command Prompt (Run as administrator)
Run SFC /SCANNOW and see if it reports “Windows Resource Protection did not find any integrity violations”.
— If it does, you won’t have to go any further but please let us know.
— If that is what happens, restart the laptop.
— I don’t know if that’s necessary to do but that is what I do anyway.
It might report “Windows Resource Protection found corrupt files and successfully repaired them.”
— After that restart the laptop.
— I don’t know if that’s necessary to do but that is what I do anyway.
— Please let us know.
— On the next day or 2nd day run SFC /SCANNOW again to ensure finding corrupt files and successfully repairing them doesn’t return because more actions will then have to be implemented.
— After that restart the laptop.
— I don’t know if that’s necessary to do but that is what I do anyway.
— Please let us know.

Then there’s running “Dism /Online /Cleanup-Image /Restorehealth” w/o the quotes if applicable.
Applicable meaning if SFC /SCANNOW doesn’t report “Windows Resource Protection did not find any integrity violations” or if “Windows Resource Protection found corrupt files and successfully repaired them.”, does return it’s time to run “Dism /Online /Cleanup-Image /Restorehealth”.
— It takes a while to run and at the end you will need to wait until you see
DISM /Online /Cleanup-Image /CheckHealth operation completed successfully.
When you reach [===100.0%===], wait a little longer to see the final reported result.
I don’t remember the exact wording of the final result as I haven’t had to use it in quite a while but wait it out and let us know the result.
Then restart the laptop.

I can’t predict how it will go for you but I do suspect that SFC /SCANNOW will not report “Windows Resource Protection did not find any integrity violations” the first time as I’ve seen that so many times. I could be wrong but I just want to bring up the reality of what you might see. I have seen people get “upset” about that but I let them know it isn’t their fault and at that point let’s hope it’s applicable to sharpen their system resources somewhat or something like that.
Good luck.

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daddybear wrote:

Is a System Restore point OK for the backup ?

Restore Point isnot a backup.
You need software and a USB hard disk for a backup.

cheers, Paul

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Let’s cover Windows Defender Quick Scan vs. Full scan.
I’m not an expert on how to explain this but in summary a Quick Scan inspects the likely areas to be infected.
— Most AV perform the same way by default.
A full scan does a complete scan off everything in the PC.
— It isn’t unusual to see as many files as you see and as long as it takes.
— I’ve just run a full scan on a PC and had similar results.
— I’d say It isn’t a matter of how slow the PC runs, it’s a matter of how long it takes to do a job that it’s called to do.
— If your PC were slow in everything else, then that’s when a slow PC needs to be addressed.
— I would leave your laptop as-is.
Check Quick Scan Vs Full Scan in Antivirus Programs
https://antivirusinsider.com/quick-scan-vs-full-scan/

On “1) We temporarily disabled Real Time Protection on Defender and then ran a full scan. It completed in 1 hour 20 mins less than before – is this a safe thing to do?
2) I have read that adding MsMpEng.exe to the Defender exclusions will effectively stop it scanning itself – do you think this would reduce the number of files involved in the scan and thus reduce the CPU load down from 100% – is it safe and is it worth a try?” in your post ##2252300.
— Don’t do that: it defeats the purpose of the Full scan and I believe it isn’t safe to do.

On Windows Defender daily scan, since your WD dashboard looks fine and since you are able to disable and most likely follow up enabled it, your Windows Defender is running fine. I believe I have read there are times that disabling Windows Defender in certain circ*mstances has been recommended but I haven’t had to do so and don’t recommend it w/o asking about it in one of AskWoody’s forum if a recommendation comes up to do that.

On “1) how do I set up Defender to run a Quick Scan on a daily basis”
— I believe it is doing that: What I suspect is the laptop isn’t reporting when WD is run in the notification area.
— Some people don’t want to be bothered by it: myself I don’t mind.

If you want to see those notifications, these are the settings on my laptop
Windows Defender dashboard > Virus and threat protection > Virus and threat protection settings > Manage settings > scroll down to Notifications > Change notification settings > next page shows Virus and threat protection notifications > my get informational notifications is On along with a few more items checked.

“where do I find the results of the Offline Scan?”
— You should find that in WD dashboard.: you might even to receive an up-front notification.
— I don’t recall exactly where as it’s been a long time since I’ve had to know that.

On SFC /SCANNOW, on the first day, you got “Windows Resource Protection found corrupt files and successfully repaired them”
— I suspected that AS at this point that isn’t unusual.
— On (tried to attach CBS Log File to this post but forum won’t allow me). That’s ok, that’s fine actually.
On the 2nd day, your “Windows Resource Protection did not find any integrity violations”
— Excellent.

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