The VRDB only run once every three weeks by default and the VRDB doesn't download, it is an integral part of avast an only scans files on your computer. The VPS is entirely different that is the Virus Pattern Signatures and they are frequently updated.
What do you mean the avast screen saver won't work with other screen savers ?
I don't use a screen saver, but the VRDB should work with any screen saver (so you don't have to use it), but you would have to wait for the next cycle to find out for sure. It isn't scanning for viruses but getting details of certain files, so that should they become infected the repair function, uses the information contained in the VRDB to try an effect a repair of the infected file.
I suggest a re-read of my first reply relating to the VRDB info in the avast Help file.