How to fix Avast Antivirus High CPU Usage

So a while back, I noticed that my CPU performance was decreased. I tested using wPRIME running a 32M benchmark. Without an Antivirus installed, I would get a score of 4.9 seconds, with Avast Antivirus Pro installed, I would get 7.5 seconds (the lower the score the better).

I then posted this thread on the avast support forums:

Avast Antivirus Pro affecting CPU Performance

No help was offered and I was just told that any Antivirus would cause a small hit on the CPU performance.

I then installed NOD32 and Kaspersky Antivirus (separately off-course) and benchmarked again but I would get 5 seconds in wPRIME so that was all good and the issue seemed to only be there when Avast Antivirus was installed.

This surprised me because according to the latest AV-Comparatives Performance tests, it shows that Avast Antivirus is one of the lightest solutions out there.

I then submitted a support ticker to Avast which as usual, took almost 2 weeks to be answered.

They suggested to change a few things which I did and now my CPU performance is back to normal, I am getting 5.3 seconds in wPRIME so a 0.3 seconds performance hit is fine.

Here are the suggestions from avast! Support to remedy this problem whilst not really affecting your security:

@Ethrem

 

I have been using Avast for years because of the low cpu usage, I get free Kaspersky though my bank but i has high cpu usage, So no problems with Avast.

I have an gadget that monitors my system top five highest cpu hogs and avast is rarly on the list.

John.

 

Right, maybe I was making this up then:

High CPU usage

Avast high usage cpu

Avastsvc.exe always at 25% CPU, even when not running anything else!

Avast Antivirus Pro affecting CPU Performance

 

Kaspersky use to use 90-100% during a scan, Avast is super light weight compared to that.

I just checked Taskmanger and it has avast using 0% cpu, as it`s not scanning at the moment, when it does scan it might go to 25% but for 15min or so and then stops, I suppose how long the scan takes depends on how fast you cpu/hdd/ssd is and how many files it has to search though.

John.

 

The right way to test it is, run wPRIME 32M benchmark with all threads which should be 8 if you have a 4 core CPU(go to settings in wPRIME) with avast! installed, then uninstall Avast and run the benchmark again, not immediately after a restart but after a few mins of being idle then see

PS: Disabling all Avast Shields doesn't count, it has to be uninstalled to see the difference before/after, if you have time to do this that is, maybe take an image before uninstalling it

 

As always, your mileage may vary. I've seen people say they dumped Avast because it was causing high CPU usage on their laptops and at the same time having tested multiple solutions, I chose Avast to run on my Atom-powered convertible, exactly because it has low CPU and very low RAM footprint while providing very good security.

I'll check those recommendations though - I think I might want to consider disabling "intelligent stream scanning" as Avast tends to eat up quite a lot of CPU when I'm downloading multiple files @ 100mbps. I'm guessing that's the reason - it attempts to scan multiple files at the same time coming at it at a steady 12MB/s

 

Good idea, please try the above recommendations and tell us if you see a difference. As support said, this will not lower your security because once the file is downloaded, if it was malicious, the active file shield will block it anyway so no harm done.

I personally dislike programs which do HTTP scanning, like I have a NOD32 license for 10 users valid until 2020 which is collecting dust as it slows down everything for me, internet browsing, downloads, etc. wish I could sell it

 

Yeah, I disable Avast bloatware app that i dont want to pay for, it`s sill not to.

Yeah, I have use Avast on my Atom cpu table as well, no high cpu usage on it`s tiny little 900 passmark cpu score, my i3 i am using now gets around 2500 points and that is quite low to most modern cpu`s

Those that use torrent downloading apps can expect to have high anti-virus cpu usage as all files need to be scanned and zip files are extracted and files scanned individually in the background this can use a lot of cpu power.

John.

EDIT: Hi i found this 2015 AV comparison test, and they also rank them by cpu usage.

http://features.en.softonic.com/windows-antivirus-comparison-2015

John.

 

@downloads

On the avast forums, one moderator said the following:

Can you please delete this thread as I don't want to cause any security risk to anyone.

Thank you

 

Let's leave it - it's valuable to know both what to and what not to do. Someone may come across it and find it valuable - granted not the way first intended.
Also Some of these tips from support remain valid - only intelligent scanning and script scanning should not be switched off it said moderator is right.

 

Turn off Avast's option to run heuristic analysis... A) it results in false positives and b) it deep scans everything in the machine... Heuristic analysis is a joke from any company except panda cloud because it chews through CPU looking for embedded virus signatures... They're so incredibly rare that 90ish percent are false positives because virus makers know how to change signatures. It's an old throwback from Windows 3.1 and DOS when the makers of the virus weren't smart enough to flip a couple bits and shuffle the program around to change the code but still have the same effect... Its useless and on first install it will run on second boot... Eats between 1 and 2 cores plus between 10 and 50MB/s of read speed from your hard drive.

 

I've been using Avast for years and it's worked really well for me on multiple machines (free version registered) but recently - last couple of weeks from memeory - it has made my day to day machine quite slow after it updated. I don't get the high CPU usage mentioned on here but pages were taking quite some time to load and it reminded me of the old US Robotics 56k modem days! WU is disabled but the machine is up to date and no telemetry and a Hosts file with the usual suspects blocked.

After reading this thread I checked the settings mentioned by Phoenix in Mail Sheild/Customise/Enable HTTPS Scanning and I disabled it to test (but left the others as they were) and this made an instant difference to browsing etc after rebooting the machine.

I use Google.co.uk as a home page (with FireFox latest) and as that is HTTPS by default I guess this could be the root of my issue as nothing else has changed on this machine and its a good spec.

Any issues leaving this scanning switched off, I'm a careful user and don't go onto any 'suspect' sites?

 

@downloads @Ethrem @Mr. Fox @toughasnails @Papusan @hmscott

New observation, without changing any of the default avast settings, Today I installed it again and ran wPRIME on 8 threads/4 cores......

My 32M benchmark got worse....

before avast = 4.65 s

after avast = 5 s

what I realized is, when I launch wPRIME, it takes a bit longer to start than usual, so that lead me to think that Avast may be scanning it or something....

Next, I added it to the exclusions of avast and ran it....

first sign was good, wPRIME launched much faster just like before I installed avast.....

then I ran the benchmark again and here are the results.....

 

Not really surprising. I always disable all shields for 10 minutes when I'm benchmarking because avast monitors everything from unusual CPU usage to RAM and everything inbetween.

 

Thanks. I tried it & it helped.

 

you're welcome.

 

My computer became completely unresponsive after running uTorrent for a significant time, even when not downloading anything. I couldn't close apps or restart. It took several tries for it to even respond to the power button. Disabling intelligent stream scanning seems to have fixed the problem for me. One of the problems with the makers of security software is that they actually believe it is more important for a computer to be completely secure than for it to be usable.

 

uTorrent IS a virus! Other than the fact that is has OpenCandy spyware bundled and hidden within it and the annoying toolbars and PUPs (potentially unwanted programs), the last time I tried it which was about 8 months ago, after using it for a while the following 2 things happened:

1) PresentationFontCache.exe started having abnormally high CPU usage causing my laptop's fans to continuously spin

2) After I reboot, it wouldn't log in to my account but rather it would say "Preparing Account" and eventually logs in to a temporary account as uTorrent has completely wiped my user account!

Due yourself a favor, uninstall uTorrent using GeekUninstaller and to get rid of all the remnants and start using uTorrent unless you want to bid farewell to your computer soon.

 

I don't have OpenCandy or any other PUPs on any of my computers. Is it possible you downloaded uTorrent from somewhere other than utorrent.com? Some download sites repackage popular freeware with their own installer and add PUPs.

 

Nope downloaded straight from uTorrent. This is not new it’s been like this since uYorrent v3. Use it at your own risk, one day you will remember me

 

So why don't I find any evidence of malware on any of my systems? And what application do you use for torrents then?

 

Why don't you find evidence of malware on your system? I don't know, I gave you my best advice to stay away from uTorrent, use what you like. I use qBittorrent