Behavior Shield Slows Win7 System Down After It Has Been Running For Days

Avast Free Antivirus / Premium Security
1

I have Windows 7 Ultimate with Avast! Internet Security on a fairly powerful 8 core workstation. I’ve used it for years, and it’s very stable and efficient.

However, I’ve noticed that my system gets slower to respond after it has been running for some days (I leave my system running and logged-in 24/7).

At this moment my system has been running for 10 days 13 hours, and when I start an Explorer window, it is taking about 4 seconds to show the window on the screen. This delay/sluggishness is occurring with opening any application - the desktop has simply become less responsive. Normally, after a fresh reboot, the time betwen starting Explorer from a desktop icon and seeing the window open is not noticeable (i.e., it’s instantaneous or at worst a small fraction of a second). The problem is NOT resolved simply by logging-off and logging back on. The problem IS resolved by a reboot.

I set out to discover what was slowing things down using ProcMon, and I noticed that LoadImage commands were each taking something like 0.1 second to complete, which adds up to several seconds overall.

Thinking about what could be affecting something as simple as loading a DLL, my thoughts turned to the Avast product, and sure enough, when I temporarily disable the “shields” the time to open an Explorer or other application window is back to being instantaneous.

A bit of further trial and error showed that just disabling the Behavior Shield averts the delay, and even further that the [ ] Monitor the system for unauthorized modifications setting is specifically responsible.

In summary:

After running Windows 7 for days (e.g., longer than a week), the Avast Behavior Shield function “Monitor the system for unauthorized modifications” setting causes big slowdowns in normal Windows desktop operations, such as starting Explorer windows.

System performance returns to normal (virtually instantaneous) after a reboot. However, I do not need nor want to reboot the system.

I am not sure whether the slowdown is progressive over time or happens all at once, but it does seem dependent on how long the system has been running since the last bootup.

Can you please advise what I can do to avert this problem without a reboot?

For now I’m working around it by disabling the specific shield function that is tied to the slowdown using the Expert configuration capabilities, but I’d like to turn that back on.

Please let me know if there is more information I could provide for you to help narrow this down.

Thank you.

-Noel

2

This is a normal issue with M$ Windows O.S. It needs to be rebooted weekly due to memory leakage. Many systems and servers have this isue. I NEVER let my systems go over 1 week without reboot.

3

I’ll check it.

4

Respectfully, thanks for your input, but I don’t believe it is correct.

I have NO other problems with or indications from Windows implying a memory resource problem, and simply clearing the Avast checkbox I mentioned restores full speed operation. The problem seems to be isolated in the specific Avast module. I’m not unwilling to believe the issue could ultimately be with resource management, but there are no indications at this time that there are such problems on my system.

I would be interested to know if Avast could be completely restarted (opposed to a complete reboot or just stopping the “shield” temporarily). I’m not sure how that could be done manually, but if it can, doing so could further prove that the problem lies within Avast, not within Windows.

-Noel

5

Have you had a chance to check this?

Thanks.

-Noel

6

I see your previous staement, and I missed that. I do not believe avast can be restarted without a reboot.

7

Thanks. I didn’t think it would be possible but I figured I’d ask.

For what it’s worth, I’ve run my system for an additional several days now without a reboot (but with the Avast setting I mentioned above disabled). It’s still light and fast, and without indications of any resource problem.

My intuition (honed by 35 years of software engineering) tells me the resource leak, or fragmentation, or WHATEVER is leading to the slowdown is inside Avast in this case.

Most folks would likely agree that a simple occasional Windows reboot is a reasonable thing, but there are reasons I do not want to do that. And I have virtually everything else tuned up and working long-term so that it is not necessary.

http://Noel.ProDigitalSoftware.com/ForumPosts/Uptime.jpg

-Noel

8

FYI, Windows Updates came in today, necessitating a reboot.

I have re-enabled the [ ] The file prevalence/reputation is low setting and now everything is still fast as ever.

So my workaround for now will be to disable this setting once the system has been running a while and I notice sluggishness. I do hope this is taken seriously and fixed in a future Avast update.

-Noel

9

It could be a corruption of the avast! load on that system, because I have never seen it before, and I have well over 20000 systems running avast. I am unaware of anyone else with this issue. There are known issues, and unknown issues. Usually unknown issues are unique to a system and therefore could be corruption. If it were my system, I would remove avast!, use ASWCLEAR in safe mode, and reinstall to prove my theory wrong.

10

Why a reboot is necssary:
http://www.upgradenrepair.com/Troubleshoot%20Tools/questions/whyreboot.htm

11

“Stuck temporary data”… Heh, that’s a good joke. :smiley:

I’m a software engineer of 35 years and now the head of a software company. Let me assure you that a reboot of Windows is NOT something that should need to be done in normal operation, and in fact has NOT needed to be done regularly since before Windows NT.

Copping out and just rebooting whenever something unexpected happens, rather than trying to discover the root cause and correct it, leads to no good.

The only thing that’s wrong here on a system running for weeks is with this specific Avast function, which is why I am posting here in the hopes that the Avast engineers will note and correct the problem.

Thanks for the smiles. ;D

-Noel

12

It could be easy to miss, in that it only adds a few seconds to interactive operations. This particular workstation is running from a big SSD array, so it does most things absolutely instantaneously. Another similar system, running spinning hard drives, takes a few seconds to do things this one does in a small fraction of a second. While a change from 0 to several seconds is pretty obvious, I suspect most users might not notice a difference from a few seconds to several more seconds to open a window. And then they might just reboot more often. How many of your users run their systems 24/7 for weeks on end without rebooting?

-Noel

13

This comment is not technically correct for it implies that it is the OS that is causing the problem and not the app. Many programs cause resource constraints due to memory leaks and some are very complex to debug because many players are involved - for example Flash and the misuse of it causes huge problems for many.

Avast definitely has a problem and it would be refreshing not to mask an error with the advice to “Reboot” for it does not help those with the issue nor Avast.

As a temporary fix I would like to understand how to quickly fix the issue for my system has gone into a never ending cycle disk access and then work on the root cause.

In my case I do not know if it was simply an update issue or what.

Even though everyone loves to slag MS the current Win 7 is far more stable than previous OS’s and memory cleanup far superior. That said I have been able to track many more apps that have issues simply because Win 7 provides much greater clarity as to which processes have started to fail.

FYI — I fixed my own problem by turning off features that were killing my performance - at this point I have no idea why my system ground to a halt today but … the only change I made was with avast and now I am fine.

14

You are commenting on outdated topics. Have you come here for help? If so, please start your own topic.

15

Hi:

I have the exact same problem with the system slowing. I use 64-bit Windows 7 Ultimate on an Intel i7 930 machin with 12GB RAM, but don’t use a SSD. The machine is pretty fast as long as I turn off all shields.

Has anyone come up with a fix for this problem?

Thanks

16

By the way I stopped having the problems I described.

I run my systems 24/7, literally going between Windows Updates or software installs- often for weeks or months - without reboots.

I fully agree that Windows does NOT inherently slow itself down, or does it corrupt itself over the long term. Users are pretty much responsible for that.

Jav, could you provide some version info about what OS you’re running, and exactly what version of Avast?

-Noel

17

My “1 minute guess” is that the Behavior Shield is caching results, and when the cache starts to get full, it bogs down trying to pop entries out of the cache to make room.

I would suggest using Process Explorer from Sysinternals.com and take a look at some of the threads inside the Avast processes.

It might also be helpful to do minidumps on the process(es) involved (right click on the process name) when it starts to slow and look at those for clues.