Author Topic: Avast! is now "slower than molasses" and reports false scan times!  (Read 39778 times)

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neiby

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Re: Avast! is now "slower than molasses" and reports false scan times!
« Reply #45 on: April 04, 2008, 07:25:22 PM »
Could it be that the first quick scan does a more complete scan and then subsequent quick scans are true quick scans? Maybe the method of folder selection really has nothing to do with it.

Offline DavidR

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Re: Avast! is now "slower than molasses" and reports false scan times!
« Reply #46 on: April 04, 2008, 07:36:00 PM »
There should be a degree of consistency, if you run two quick scans one after the other they should return the same file/folder results (IMHO).

The same should be true of folder selection if they cover the same drives/partitions and you are using the Quick level of sensitivity and archives not selected. The files scanned should really revolve around the sensitivity and if archives are selected or not.

Otherwise I wouldn't see why Igor would suggest the test if the file/folder results were going to be so different.
Could somebody please confirm (or deny) that the slowdown of the quick scan occurs only when "All local disks" are selected to be scanned - while if you go to folder selection, and select all your local disks from there, it doesn't occur?
« Last Edit: April 04, 2008, 07:59:37 PM by DavidR »
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Offline Lisandro

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Re: Avast! is now "slower than molasses" and reports false scan times!
« Reply #47 on: April 04, 2008, 07:55:28 PM »
I've selected C:\Program files and C:\Windows to be scanned thoroughly.
It's taking an eternity to finish with Simple User Interface (4 hours for 50% of the files...).
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Offline DavidR

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Re: Avast! is now "slower than molasses" and reports false scan times!
« Reply #48 on: April 04, 2008, 08:00:37 PM »
I haven't got the patience for a thorough scan and I have much less data on my system I believe.
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Offline igor

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Re: Avast! is now "slower than molasses" and reports false scan times!
« Reply #49 on: April 04, 2008, 08:17:02 PM »
Well, I found a possible problem related to the progress display, where a "quick scan" scans more thing than it used to previously. It occurs only when scanning through "Local disks" area (simply speaking).

I have also been able to simulate a slowdown on one old virtual machine... but I have no idea what's the problem yet. It's gonna be kinda tricky, I'm afraid.

Offline Lisandro

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Re: Avast! is now "slower than molasses" and reports false scan times!
« Reply #50 on: April 04, 2008, 09:00:51 PM »
I've selected C:\Program files and C:\Windows to be scanned thoroughly.
It's taking an eternity to finish with Simple User Interface (4 hours for 50% of the files...).
5 hours and 56%...
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neiby

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Re: Avast! is now "slower than molasses" and reports false scan times!
« Reply #51 on: April 04, 2008, 11:35:44 PM »
I just ran a standard scan with no archives and it was exactly the same amount of time (and total file size) as when I ran the quick scan for the first time. I think the program is doing a standard scan the first time you do it even if you select quick scan. Subsequent quick scans are actual quick scans.

Offline essexboy

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Re: Avast! is now "slower than molasses" and reports false scan times!
« Reply #52 on: April 04, 2008, 11:56:28 PM »
To be honest I haven't noticed any slow downs - but I have Avast set to scan when the screen saver is on, otherwise I just use ashquick with my download manager and that seems fast enough.  Every fourth sunday I do a boot scan when I read the paper - that is due this week so I will check it then  :D  smile people   

Offline Lisandro

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Re: Avast! is now "slower than molasses" and reports false scan times!
« Reply #53 on: April 05, 2008, 04:01:32 AM »
I've selected C:\Program files and C:\Windows to be scanned thoroughly.
It's taking an eternity to finish with Simple User Interface (4 hours for 50% of the files...).
5 hours and 56%...
10 hours and 40 minutes to finish... it's really slow! :P
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Offline alanrf

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Re: Avast! is now "slower than molasses" and reports false scan times!
« Reply #54 on: April 05, 2008, 07:00:10 AM »
Tech,

earlier you asked for a baseline - well there is one.

I know that the following is not news to you but I want any other readers to understand.

Remember that we have two programs in avast that drive on demand scanning. 

1) ashsimpl.exe - this manages the classic scanning with options for Quick, Standard and Thorough scans and with archive scanning optional in each of those scan levels.  Scanning can be performed on all local drives, selected drives and/or selected folders.

2) ashquick.exe - this manages ad-hoc scanning and its options are fixed at Thoroughl scan with archive scanning.  This scanner is the one most often used to scan newly downloaded files and is the program used for the shell extension scanning when you right click on a drive, folder or file. 

While both of these functions have been modified in avast 4.8 to include scan progress information to the best I can tell there has been no degradation of the performance of ashquick.exe.  It appears to me that there is significant degradation of the performance of ashsimpl.exe compared with its performance in avast 4.7. 

So back to that baseline. 

In a system with avast 4.7 installed if you perform an asquick scan of say C:\Program Files then it will scan that folder and all the folders within it.  It will run for a given time and report on the files/folders scanned the total disk space scanned and the number of infected files found.  If you then use the ashsimpl.exe interface and run a Thorough scan with archive scanning of the same folder it will run for a very roughly similar time to ashquick and give statistics very close to those of ashquick.exe for scanning the same.

In a system with avast 4.8 installed, as far as I can tell, an ashquick.exe scan of say c:\Program Files will run for about the same time as it took in the 4.7 version.  This is the baseline - this is what avast's scanning code can achieve in avast 4.8. 

If you then run an equivalent ashsimpl.exe scan of C:\Program Files and select Thorough scan with archive scanning (to match what ashquick.exe does) then you will see the considerable degradation of the performance of this scan in avast 4.8 compared with avast 4.7.  I believe that all levels of the scanning by ashsimpl.exe are considerably less efficient than they were in avast 4.7 (irrespective of whether all local drives or selected folders are scanned).

Now my guesses ...

I do not think that there is any problem with the scanning of individual files being slower.  I do not think that this is a rootkit scanning overhead problem (look how fast the standalone rootkit scanner is).  It does appear from traces that something is taking up time between scanning of files - that may be something to do with the way the scan progress indicator has been implemented in ashsimpl.exe - the scan progress indicator in ashquick.exe does not seem to involve any delays between the processing of files.

Of course my guesses are irrelevant.  What matters is the team getting in any finding the real cause. 

Earlier tonight my full system scan using ashquick (as I do every week) completed in 34 minutes, the same time as it took with avast 4.7.  I then ran an ashsimpl scan at Thorough with archive scanning (just as ashquick had done).  I cancelled it after it had been running more than 2.5 hours and it said that it was 39% complete.

Tech, you may want to run an ashquick scan of your system and see what the difference is from that 10:40:++
« Last Edit: April 05, 2008, 07:40:45 AM by alanrf »

Offline cheater87

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Re: Avast! is now "slower than molasses" and reports false scan times!
« Reply #55 on: April 05, 2008, 07:34:34 AM »
My standard scan takes twice as long. It used to be about 20 minutes or so and now its in the 40s.
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Offline Lisandro

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Re: Avast! is now "slower than molasses" and reports false scan times!
« Reply #56 on: April 05, 2008, 02:41:54 PM »
I believe that all levels of the scanning by ashsimpl.exe are considerably less efficient than they were in avast 4.7 (irrespective of whether all local drives or selected folders are scanned).
I'm experiencing the same. What I can add is that seems the Enhanced Interface scans quickly at the same level (or even deeper) than the Simple User Interface scanning.

Tech, you may want to run an ashquick scan of your system and see what the difference is from that 10:40:++
I'll test it with:
"C:\Program Files\Alwil Software\Avast4\ashQuick.exe" "C:\Program files\*" "C:\Windows\*"
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Offline Lisandro

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Re: Avast! is now "slower than molasses" and reports false scan times!
« Reply #57 on: April 05, 2008, 03:41:53 PM »
I'll test it with:
"C:\Program Files\Alwil Software\Avast4\ashQuick.exe" "C:\Program files\*" "C:\Windows\*"
Exactly 1h and 1 minute! Something very different than 10h+
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Offline igor

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Re: Avast! is now "slower than molasses" and reports false scan times!
« Reply #58 on: April 05, 2008, 04:08:58 PM »
Did you use the skinned Simple UI?
Does it make any difference if you use the skinless with the same settings? (and folder selection if it's a quick scan, not "local disks")

neiby

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Re: Avast! is now "slower than molasses" and reports false scan times!
« Reply #59 on: April 05, 2008, 04:30:24 PM »
I always use the no-skin version of Avast.

I just tried another quick scan by selecting Local Disks, no archives. It looks to me like if you select that option for a quick scan, Avast actually does a standard scan instead.