Author Topic: Avast Causing Computer Slow Downs  (Read 632 times)

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Offline hitaka5ever

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Avast Causing Computer Slow Downs
« on: December 09, 2020, 12:14:45 AM »
Hello, I got the recent free Avast for Windows 10 and it has significantly slowed down my computer when it never used to. Here's a screencap of the CPU and Memory that has been taken over by Avast

Is there anything I can do aside from rolling back to a previous build?

Offline Asyn

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Re: Avast Causing Computer Slow Downs
« Reply #1 on: December 09, 2020, 07:05:20 AM »
- Which Avast..? (Free/Premium)
- Which version/build of Avast..?
- OS..? (32/64 Bit..? - which SP/Build..?)
- Other security related software installed..?
- Which AV(s) did you use before Avast..?
Win 8.1 [x64] - Avast PremSec 21.3.2459.BUC [UI.612] - EEK - Firefox ESR 78.9 [NS/uBO/PB] - TB 78.9
Avast-Tools: Secure Browser 89.1 - Cleanup 21.1 - SecureLine 5.11 - Driver Updater 21.1 - CCleaner 5.78
Avast Wissenswertes (Downloads, Anleitungen & Infos):

Offline darkwaechter

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Re: Avast Causing Computer Slow Downs
« Reply #2 on: December 10, 2020, 03:27:17 PM »
This is exactly the memory leak problem !
It happen's since 20.7 and it works after disabling the proxy detection under Windows.

See following post from topic "RAM usage problem after upgra NEW Avast Version 20.7.2425" :

I found the the source of the problem, is the wpad.dat file used to auto define the proxy (or no proxy).

Sorry for delay.
Version 20.8.5684.602  not solved my situation.  Same behavior, soon I connect network cable Avsta start eating all memory.
It happens on some networks, not on others.  Or start after some time.
My network are the culprit? Why special have on these networks?

My test procedure is this:
Disable swap/paging on window, avoid system to use paging, a avast just eat all ram and killed by the kernel (I think). 
Start computer with network cable disconnected (no wifi).
Open taskmanager, and Avast GUI.
Connect network cable and watch rise of memory usage by Avast.

If have some thing on my network causing the Avast memory issue, what can be?
My firewall is a linux machine, very simple, just for NAT, no complex packet filtering, multi internet access and Squid proxy (all most disabled).
I drop all forwarding from offending host. No change.
Dropped all input to firewall. NOW, avast no eating memory.
I opened port 80, and Avast start eating memory again.  What Avast accessing? Check the webserver log.
Avast getting the wpad file for proxy definition on this network. Renamed wpad.dat file, and try again.
Whitout wpad, no problem, avast try to get file, get a 404 and nothing happens.

Code: [Select]
The log on webserver (lighttpd 1.4.19): wpad - [09/Oct/2020:09:36:43 -0300] "GET /wpad.dat HTTP/1.1" 200 94 "-" "Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.3.3626.1895 Safari/537.36 Avastium (20.8.2432)"

wpad.dat content:

function FindProxyForURL(url, host)
         return "DIRECT";

I hope this information helps to solve the problem.

Tanks, Paulino.

I confirm, it comes from the proxy !

Disabling the option "Automatically detect settings" of proxy under Windows, will no more cause the memory leak.
Activating it again, and Avast eats again all memory ...