Avast! free SCAN Speed issue

[gabrielveras]

Every time I start a scan, it goes at about 300MB/second for a couple of minutes, and then the speed starts going down gradually, reaching about 20 MB/second wich is really annoying, cause it scans half the pc in minutes, and then takes hours to scan the other half.

Is this normal? Is there something I can do to make the speed constant?

Any help would be greatly appreciated. Ty.

[CraigB]

Have you modified any of the default settings in any way, the speed does gradualy reduce but scans shouldn't take to long unless you have huge amount's of data on you disc's.

[gabrielveras]

The only thing i changed was the scan piority from normal to high in the "performance" setting.

Right now i´m using about 200/500 GB from the disc. So, it´s normal for the speed to tank like that?

[CraigB]

That is a fair amount of data, im only using 20/500 and my scan's take about 15 min's and when the scan uncompresses and read's the data it end's up around 30gig that it has read so you having 200gig would take a considerable amount of time.