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Aspiring Contributor
Message 1 of 13

mcshield.exe is hogging my CPU

I installed BT NetProtectPlus a week or so ago and I started immediately noticed my system slowed down. I've been monitoring Windows Task Manager and mcshield.exe seems to be the main problem (I'm seeing 80-100%of my CPU taken up with it). I have switched off site monitoring (not sure of the correct name for this) but can see no performance improvement.


The problem is noticeable in all situations e.g. When browsing the web, when I bring my PC out of hibernation but it also is evident even when I come to use the PC when it's been on for 30 minutes or more. Video playing is jerky.


Here are a few details of my system -


Windows XP, Version 2002. Service Pack 3

AMD Athlon 64 CPU 3200+ (2.19GHz)

Available RAM 2.3 Gigabytes 


I hope something can be done to minimise this problem! I'd appreciate any assistance.


Thanks in advance.

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Recognised Expert
Message 2 of 13

Re: mcshield.exe is hogging my CPU

Hi User47,


Have you checked the virus scan schedule to make sure that a scan isn't scheduled on startup?




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Message 3 of 13

Re: mcshield.exe is hogging my CPU

"mcshield.exe" is the McAfee On-Access Antivirus Scanner from Network Associates, Inc. - part of McAfee VirusScan.


It sounds to me like it's running amok and scanning every file on your system as it's being accessed by your computer, which is totally OTT.


You need to tweak VirusScans settings ie: turn on-access scanning off, or modify the way it operates.

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Message 4 of 13

Re: mcshield.exe is hogging my CPU

I had McAfee installed on three of my company PC's - each and every one started to run slower and slower, all down to McAfee - uninstalled and tried several others, such as CA Antivirus and Avast (not great) and actually found the least 'intrusive' and the one that consistently used much less resources was Microsoft Security Essentials (MSE) - not everyones cup of tea obviously as it's from Microsoft, but I can only speak as I find, and it's been the best of the bunch and is FREE.

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Aspiring Contributor
Message 5 of 13

Re: mcshield.exe is hogging my CPU

Thanks for the replies. I'll check my settings and see how things go. Cheers!

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Message 6 of 13

Re: mcshield.exe is hogging my CPU

Thanks to everyone for raising this issue and trying to address it. Since I installed McAfee 3 weeks ago, everything has been very slow. It takes more than 30 minutes to get my Internet Explorer initial webpage. I have disabled real time scanning - impossible to work on even simple, pre-existing, already scanned self-created documents. I have also now disabled scheduled scanning. If your computer is not on when the scan is scheduled, it starts scanning as soon as you start your computer and everything is frozen or extremely slow.  Even if you select "scan in background" everything is still extremely slow. Even trying to click the menu items on McAfee or trying to stop the scan is not responsive. When it did the initial full scan, it took more than 2 hours. My operating system is Vista Business. Having read all your contributions, I'm going to uninstall McAfee. I might try the Microsoft Security Essentials which several contributors have mentioned favourably. I can't believe Microsoft is inspiring recommendations rather than gripes! If so the Security Essentials must be good.

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Aspiring Contributor
Message 7 of 13

Re: mcshield.exe is hogging my CPU

All these weeks on and my problem still exists.


I've unchecked most of the options in Real-Time scanning but I've not switched it off altogether as I'm wary of doing that.


Is there onyone from Mcafee who reads these forums or even someone from BT who can comment? Surely there must be a solution!





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Distinguished Guru
Message 8 of 13

Re: mcshield.exe is hogging my CPU



This is an ongoing issue.


There is a 41 page thread on the Mcafee forums.


They are apparently testing an update.


The latest page is here -


If you click page 1, you'll see it's been a known issue since 05 May 2010


I'd keep this bookmarked and keep checking it

-+-No longer a forum member-+-
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Aspiring Contributor
Message 9 of 13

Re: mcshield.exe is hogging my CPU

I would not recommend turning On-Access scanning off as this is your primary defence against malware. In any case this would not use a lot of resources.


I'm not familiar with the version of McAfee you are using as I use the Viruscan Enterprise version but you may be able to tweak the CPU usage during a scheduled scan so it uses less CPU (I do this to keep the fan quiet and so as to not degrade performance). However, the scan will, obviously, take longer. I have a fairly lighly loaded machine (files total about 50GB on the c drive) and a typical scan can take an hour or so so. If you have hundreds of Gigs then scanning could take some time. McAfee usually includes a log of activity soe you could also consult that to see what it is doing and how long it's taking.


If you can then change the schedule to scan overnight.


Of course, I'm not ruling out a race condition due to a bug in McAfee - this could also be the problem - but is less likely than an unthrottled scan of a very large volume of storage.

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Aspiring Contributor
Message 10 of 13

Re: mcshield.exe is hogging my CPU

Thanks for the replies -


DS - thanks for the link to the Macafee forums. I see what you mean! This is a shocking situation!!


Mordag - thanks for the advice, I won't switch On-Access scanning off especially now that I know it's the primary defence against malware. But when you say this would not use a lot of resources I find that when I start navigating web pages it's very heavy on my CPU. This isn't a scheduled scan as I can see when that's running but some kind of real-time scanning I assume. (I do have a hundreds of gigs for the scheduled scan to get through but I let that run through the night every 2 weeks so I'm ok with that).


Anyway, at least I'm now aware of the wider scale of this issue and that is useful.



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