Maybe Not-->Quick Scan takes longer than Standard Scan

Avast Free Antivirus / Premium Security
1

I recently did a Quick Scan (w/o scanning archive files) and then a Standard scan (w/o scanning archive files) a little later the same day. The results were interesting. Both scans used
VPS: 080923-0, 09/23/2008 with product version 4.8.1229
WinXP Home SP2 with up to date patches.

Summary from QUICK Scan:
Infected files: 0
Total files: 27400
Total folders: 10281
Total size: 7.7 GB

  • Task stopped: Tuesday, September 23, 2008 8:43:24 AM
  • Run-time was 24 minute(s), 20 second(s)

Summary From Standard Scan:
Infected files: 0
Total files: 95783
Total folders: 10457
Total size: 40.1 GB

  • Task stopped: Tuesday, September 23, 2008 2:26:09 PM
  • Run-time was 20 minute(s), 23 second(s)

Clearly the standard scan scanned a whole lot more files but took 4 minutes less time.
I’ve repeated this test more than once with similar results.

So, what is so quick about a quick scan?

–Larry

2

Firstly this isn’t acting as it should.
Some time ago this was also reported extensively and there were changes made to correct this and the Quick was quicker than the Standard scan again, so I don’t know what is going on for this to revert on your system.

See the help file (Simple User Interface > Working with avast! 4 in the Simple User Interface) for the differences in Quick, Standard and Thorough scans.

Though I generally only do a Standard Scan without archives, I did a Quick scan and it took marginally less time than my normal Standard Scan even though the amount of data was much less…

I don’t have a huge amount of data to be scanned and I have a relatively fast system.

3

My experience today VPS: 080924-1, 09/24/2008

Summary from Quick scan:

Infected files: 0
Total files: 19727
Total folders: 4983
Total size: 9.4 GB

  • Task stopped: Wednesday, September 24, 2008 16:33:20
  • Run-time was 9 minute(s), 34 second(s)

Summary from Standard scan:

Infected files: 0
Total files: 45918
Total folders: 4984
Total size: 14.1 GB

  • Task stopped: Wednesday, September 24, 2008 17:04:28
  • Run-time was 13 minute(s), 16 second(s)
4

My Results - XP-Home SP3, 2.4GHz Core 2 Duo, 1GB memory

VPS: 080924-1, 24/09/2008

Quick scan:

Total files: 17155
Total folders: 2931
Total size: 3.9 GB
Runtime: 00:06.23

Standard scan:

Total files: 34882
Total folders: 2931
Total size: 6.2 GB
Runtime: 00:08.15

5

It’s interesting to see the other folks timing results. I decided to do a more controlled test. It’s possible I was using the PC for other work during the scans I reported in my OP. So, today I stopped all the other processes and did two back to back scans (Quick and Standard). I even exited avast after the first scan and then started it anew for the second scan. Nothing ran while the scans were in progress.

Results look better:

  • Task ‘Simple user interface’ used
  • Started on Thursday, September 25, 2008 12:15:27 PM
  • VPS: 080925-0, 09/25/2008

QUICK SCAN:

Infected files: 0
Total files: 27674
Total folders: 10474
Total size: 7.8 GB

  • Run-time was 14 minute(s), 39 second(s)

STANDARD SCAN:

Infected files: 0
Total files: 96052
Total folders: 10475
Total size: 40.3 GB

  • Run-time was 20 minute(s), 37 second(s)

So this time the QUICK scan was actually quicker. But if you look at it as GB/second scanned, the results are:

QUICK: .00887 GB/sec
STANDARD: .03258 GB/sec

The standard scan rate is about 3.7 times faster than the quick scan rate.
I did this by looking at the total sizes and times reported for each scan.

Doing the same calculations on the results posted by alanrf and olddog show that the scan rates for the quick and standard scans are all in the .01xxxx GB/sec rate which is about what my quick scan rate was.

I guess I should be happy that my standard scan rate is over 3X what the other posters got.

– Larry