How to Keep Microsoft Security Essentials from Slowing Down Your System

Microsoft Security Essentials (MSE)  is Gizmo’s Freeware Product of the Year for 2010. Recently, a new version came out and it has a setting that can be very useful to owners of older, slower PCs or netbooks.

Even when an efficient antivirus program does a scan, it can use enough system resources to cause a noticeable slowdown of older machines. Version 2 of MSE has a setting that can cut down the impact that a scan has on the system. The amount of CPU time allocated to the scan can be limited. While it won’t make much difference in a new quad-core machine, it can keep an old single-core system or a netbook from bogging down and allow you to continue to work during a scan. There is a tradeoff—using less CPU time means taking longer to finish a scan.

To configure the settings, open MSE and select the “Settings” tab. As the figure below shows, you can adjust the amount of CPU time devoted to a scan in a drop-down menu. The default setting seems to be 50%. If limiting the CPU is not important in your particular system, remove the check by “Limit CPU usage during scan”. That will speed up your scans.

Microsoft Security Essentials CPU setting

By experimenting with this CPU setting, you should be able to find one that is best for your particular system.

This tips section is maintained by Vic Laurie. Vic runs a Windows blog called The PC Informant and also operates a computer education website.

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by Amillennialist (not verified) on 19. June 2012 - 7:20  (95103)

Running Windows 7 x64.

When MSE's Real-Time Protection was enabled, it took forever for Start Menu icons to load. Disabled Real-Time Protection, and the icons loaded right away.

I tried Avira, and icons still loaded slowly.

Now, I'm running Avast!, and the icons load almost instantly the first time a directory is accessed; after that, they load instantaneously.



by Lucid transition (not verified) on 27. December 2011 - 2:20  (86030)

My computer was running like sh** for a few weeks.. The instant I uninstalled this program, the vids i was trying to watch online instantly (in the background)started playing as they normally would instead of buffering constantly. That was enough proof to me that its more of a problem than a solution. My advice, Uninstall this junk the split second you get it. I use Malwarebytes ONLY, and my computer runs smooth as glass. Pay attention to your updates, it will still try to install itself during them.

by MidnightCowboy on 27. December 2011 - 4:35  (86033)

The free version of Malwarebytes contains no real time protection component. We therefore advise users to seek an alternative that does from our selection here:

by P. Eim (not verified) on 2. May 2011 - 21:27  (71308)

I very happily use, KFCdotEXE, MalwareBytes, Ms Security Essentials, and Windows Maliscious Software Removal tool. They do not seem to byte eachother and have been keeping my system very, very clean.

{Moderator's Comment: References to some software not acceptable on this site removed.}

by P. Eim (not verified) on 3. May 2011 - 0:25  (71312)

Why are the ones you left acceptable, and the others I stated not? TThey are all free to download to all

by MidnightCowboy on 3. May 2011 - 6:52  (71327)

Our moderators decide on the acceptability of content based on site policy which will not be discussed here. If you wish a personal response, register and send a PM to either myself or one of the moderating team.

by jeepmanjr (not verified) on 2. February 2011 - 1:51  (65665)

How to keep MSE from slowing your system down? That's an easy one. Don't install it. Sorry, that's my answer to most things M$. There is plenty of other good software out there.

by Errol Greer (not verified) on 29. January 2011 - 12:59  (65430)

I run Comodo Internet Security Premium Ver 5.3 and MS Security Essentials Ver 2 together. Is this OK ? MS Security Essentials slows down everything just after a reboot, but eventually (about 5 - 10 minutes later) seems to settle down.

by MidnightCowboy on 29. January 2011 - 14:31  (65440)

If you have the full Comodo suite including the antivirus then this will eventually cause conflicts in your system.

All vendors advise against running two antivirus programs in real time because of the conflict risk and because protection is likely to be worse rather than better as both applications compete for system resources and file access.

by castiel (not verified) on 28. February 2011 - 3:15  (67178)

Some vendors will advise not to use their AV in combination with other product simply because they're competitors but to say in general that It will post harm than good for me I think is an over-statement

I'm using Avira Free + MSE in my system with both real-time protection enabled and yes, they do have some file access conflicts but it is not more of a problem but rather than a confirmation that the file being scan is really malicious. Also, I'm into the thinking of if the first AV missed it, there is a chance that the second AV will not.

by MidnightCowboy on 28. February 2011 - 6:46  (67183)

Unfortunately this is not the case. Yes, there are strong competitions within the industry and some vendors are more reliable and trustworthy than others. That said, there are others which are 100% genuine and yet they all say the same thing. Most vendors will also supply you with the technical details explaining why running two AV's in real time is more likely to reduce your protection than improve it. The fact that some people will state the opposite is because they want to believe it. One AV is real time is all that is required.

by syntax_error on 27. January 2011 - 0:54  (65267)

The tip is for adjusting CPU usage during scans, however in the same graphic of the setting screen is an example of scheduling a scan for 2.00 am on a Sunday morning.

For me this is the best way, schedule a full scan weekly at a time you will not be using the PC. Then you would not care what the CPU does.

by zheng ye (not verified) on 26. January 2011 - 23:47  (65263)

Is the percentage one selects to be the amount of CPU which MSE is allowed, or which one wishes to reserve for other applications??
Obviously at 50% it doesn't matter, does it, but in any other case, it does.

by v.laurie on 26. January 2011 - 23:55  (65264)

It's the amount allocated to MSE. If you have a multi-core, mult-threaded CPU, I don't know exactly how the allocation works out.

by Mikc (not verified) on 26. January 2011 - 21:51  (65258)

By current Benchmarks my PC is "an old banger" - consequently MSSE often clogs the Operating System to almost standstill. This Tweak will now allow it to operate on as low as 10% CPU resources while chugging away at background protection.

by SteveinDallas (not verified) on 26. January 2011 - 19:05  (65244)

Here is a general technique that can be used to tame a program or process that's hogging the CPU landscape:

Control-Alt-Delete and click Start Task Manager

Click Processes Tab

Right click on the specific process you want to alter

Move curser to Set Priority

Click on a low priority level to tame a maniac process thats hogging all the CPU time or a high priority to speed up a process you want to run ahead of all its friends.

I don't know if this works for everything but it has worked for a few on my computer. There are lots of guys here smarter than me that could amplify.

by Ronaldo (not verified) on 27. January 2011 - 21:57  (65331)

Or get Process Tamer is a tiny (140k) and super efficient utility for Microsoft Windows XP/2K/NT/Vista/Win7 that runs in your system tray and constantly monitors the cpu usage of other processes. When it sees a process that is overloading your cpu, it reduces the priority of that process temporarily, until its cpu usage returns to a reasonable level.

by Ronaldo (not verified) on 26. January 2011 - 18:18  (65241)

This has to be the best tip ever! Finally Microsoft has done something about their CPU hogging programs and given us an option. Wonder when they will start charging for this?


by MikeR (not verified) on 26. January 2011 - 16:03  (65235)

Great tip, much-o appreciated as we're coming to the end of our subscription to Online Armor ++ and don't see much point in renewing, even at the discount price of $30, for my wife's laptop (which she uses to visit such naughty websites as BBC Good Food and a gardening forum.)

Her lappy is on XP / SP3 so MSE plus the built-in Windows Firewall will be fine. And as a single core, four year old machine, the CPU tip is applicable in our case.

Incidentally. . . re the number of posts on here asking whether doubling up of AVs and / or firewalls is a good thing. Ye Gods, obviously it's not. And yet, and yet, how "obvious" that is to so many computer users is a moot point: last month I "mended" a friend's PC that was running Norton (aargh) as well as AVG AV, and then yesterday, "mended" my neighbour's PC which was running Windows Firewall, Comodo Firewall, Avast and Avira AVs simultaneously. Some kind of record, that.

by Jcb Kent (not verified) on 26. January 2011 - 14:44  (65228)

So simple and straightforward, but I have been wracking my brain since I installed the MSE, not putting together the incredibly slow performance with the new programme. I too have Avir and Avast as well, so pwrhaps do not need all of them?

by v.laurie on 26. January 2011 - 14:55  (65230)

It is not a good idea to have more than one antivirus program running at the same time.

by RedSkywalker on 26. January 2011 - 13:46  (65225)

Doh! so simple but why on earth didn't I think of that! cheers.

by ABC (not verified) on 26. January 2011 - 2:47  (65210)

Where would it be located on my pc? I found it once before so I must have it installed..... thank you.

by v.laurie on 26. January 2011 - 3:26  (65212)

See if there is an icon in your system tray (also called the notification area). It'll be green if you are up to date. Right-click the icon and then "Open".If you can't find the icon, type "security" into the search box (Windows Vista/7) Or look in the Programs folder.

by Chip W (not verified) on 25. January 2011 - 6:14  (65157)

I inadvertently had Microsoft Security Essentials and Avira running at the same time. My computer ran like molasses. Like molasses I tell you!

by J_L on 24. January 2011 - 21:07  (65142)

That only affects your system when you've initiated a scan with MSE.

A much better way to reduce its resource usage is to make its real-time protection monitor incoming files only. That makes it ignore files already in your system and focus on new files created. Only use that setting on a clean computer.

by syntax_error on 26. January 2011 - 1:39  (65205)

"Only use that setting on a clean computer."

What if you do a full scan first, then set as you suggest?

Edit: I may have misunderstood clean computer, I read it as a new set-up.

by Wineman (not verified) on 26. January 2011 - 14:34  (65227)

Sorry for the double post. I had meant to reply instead of doing a new post.

The only problem with just doing a full scan first is the possibility that it misses something. With a freshly formatted system you pretty much know that you're good to go. It would be best to already have the program saved to a thumbdrive or whatever so that you can install it before you connect to the internet the first time.

Does anyone know if it interacts well with Avira AntiVir Personal?

I seem to remember another way of adjusting CPU allowance for programs, but can't remember how exactly. I'm thinking it's through the task manager.

by MidnightCowboy on 26. January 2011 - 14:46  (65229)

You might find this interesting - it's just yet another article on the same subject.

All the vendors I've ever spoken to say running two products like this in real time will eventually cause conflicts and lower protection instead of increasing it.

by jason on 27. January 2011 - 3:19  (65272)

"conflicts" is probably not the right word to describe it. Running multiple antivirus/antimalware solutions at the same time means they will both want to be in memory, they will both want to scan files, and use cpu cycles at around the same time - effectively using resources that would be put to better use if just one application could have "everything" rather than "share".

The result is that both applications perform slower and less efficiently that if either didn't have to share resources. When applications like these are set to do real time scanning (scan each file before allowing a read or write to occur) if they run more slowly, then the system becomes less responsive.

In a nutshell - it takes longer to perform an operation twice instead of once - especially if you are being powered with only half the available resources - that you would otherwise have if you were running solo.

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