... after some more tests the result is a real shame. while I am now writing this, I should work on a different PC; I had started there with looking up something on the web and writing something in a simple text file. I had to wait for about 2 to 3 minutes to be able to save the text (i.e. duration between invoking save-dialogue and appearance of the save-window). The PC is still not yet usable; just scrolling on a website takes several minutes until the page moves.
Sorry but that is NOT multitasking as it should be!
Btw: the only solution is to quit EVERY AND ALL PROGRAMS before manually starting the update process, then the wait period is only about 2 minutes. But while updating just virus definitions, the PC is absolutely not usable; the more you do the longer it takes!
The new values:
Engine and definitions: previous 130830-1, updated to 130902-0
Total time: 31:49 (!!!!!!!!!!!!!!!!!)
Download time: 26 s (!!!!!!!!!!!!!!!)
Downloaded files: 19 (1493.42 KB)
Server: download354.avast.com (46.165.210.3)
And during that half hour the PC was not usable!
I can present you the screen-shot if necessary!
And next time I can run videocam to record it!
(btw: two weeks ago I followed your instructions!)
More than half an hour for something that was downloaded in even not half a minute?

How crazy are you?

To be honest, but that behavoiur is a real shame - sorry for telling you that!
Btw: sorry, I was wrong above: as I remember there was no AV-software installed before AVAST, and it started with v5 or v6, but not v4