I note that the review/article date is 21/01/2010, so that would be one of the very first release builds, the latest build 5.0.462 had a number of fixes and improvements.
So it might be nice to see if the scan duration that the reviewer felt took quite a while, would see any improvement. Personally my scans over time with the compilation of the persistent cache function much faster than a roughly equivalent scan in 4.8.
Whilst the reviewer also mentions the AV-Comparatives tests measuring performance impact, avast did particularly well in the speed of its on-demand scan in comparison to many of the other AVs. So I don’t know what setup he had, etc.