I usually run Full system scans, and recently my scans take a significant amount of time (~1 hour) to progress past 0%. After progressing past 0% the progress meter seems to increment normally. I am scanning around 300 GB of files and am wondering if I should be worried that the scan takes so long to leave 0% and if that’s normal.
I also does seem like the scan is scanning the all the files twice. Once before it leaves 0% and once afterwards.
Update: The progress meter has gone backwards from 50% to 26% after it has found infected files. Is that normal as well?
Whilst I don’t work for avast I suspect that, before the time/percentage done/remaining can be displayed it would have to analyse the data that you want to scan.
If infected files are found then the avast scan goes to a much higher degree of sensitivity/thoroughness - almost paranoid mode. This would not only take longer it could also mean that more data is going to be scanned, hence the revised figure of how much has been scanned.
Personally - 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 used to have avast set to do a scheduled weekly Quick scan, set at a time and day that I know the computer will be on. But I have ceased this practice for some time now, based in the above.