I have been using Avast since v.5, at least, and v.7 was fine. Problems started as I “upgraded” top v.8. As AntiVirus, I don’t have a negative reaction, but since v.8, my computer slowed down, and more important scanning is a drag. My computer is old, and there is no way around that, if I want to keep it (I am 81, and money does not grow on trees!), but things have changed to the point that I removed Avast three times since it came out, but nothing else satisfied me.
I like to do a Custom scan, which other Antivirus programs do not offer to be scheduled. But the time that it takes to do a Custom scan is incredible. With Avast 7, I was going at a rate of nearly 10 MB/sec. Since Avast 8, it rarely, went over 3.0 MB/sec. And, the last scan did nothing for 41 min. I have about 55 GB on my drive, using WinXP-SP3, and my custom scan goes over 25 GBs. In the last hour, the scan has not budged from 94% ( % of what?), and has gone for nearly 3 hours.
Other than scanning speed, Avast or my Computer, for that matter have been ok.
Is Avast 7 still available? And working at the same rate as before? I succeeded in installing Avast 7, oce before, but Avast did not stop bugging me!
It might be a good idea if you told us what you’re settings are for your custom scan. Someone may offer a suggestion as to how to
speed things up. 
It might be a good idea if you told us what you're settings are for your custom scan. Someone may offer a suggestion as to how to speed things up.
You got it! Even before seeing your reply, I went to my Settings. And, I found changes which I had not made. Instead of the chosen Fast Scan, I saw the slow option. Also, I wanted to make some additions or subtractions to to the folders being scanned, and I saw nothing. I had noticed this behavior before, but not so extreme. So, I had to set up a new Custom Scan, presumably scanning the same folders as before, and the fast option. I got done in less than one hour, scanning half as many folders. Avast custom scanning may be good, but it is very unstable. I might as well take the Quick Scan, but, then Avast is no better than otherAntiVirus programs, in this feature.
In all honesty, “I might as well take the Quick Scan, but, then Avast is no better than other AntiVirus programs, in this feature.” I think you have the wrong view of on-demand scanning. The depth of the scan I would say is to a lessor degree not as important as detection.
- With a resident on-access antivirus like avast, the need for frequent on-demand scans is much depreciated. For the most part the on-demand scan is going to be scanning files that would be otherwise be dormant or inert. If they were active files then the on-access file system shield would be scanning them before being created, modified, opened or executed.
I have avast set to do a scheduled weekly Quick scan, set at a time and day that I know the computer will be on. If for some reason my system wasn’t on, no big deal I will catch up on the next scheduled scan.
You also don’t give any in details on your custom settings and what this instability is ?