i have set vrdb to generate manually
and when i press generate vrdb now
my computers starts to go slower and slower i cant start program and not close down program and after some seconds the only thing i can do is to tab between the programs that is open but i cant use them because they are not responding everytime i start vrdb this happen
running the latest
4.7.1098 version
how much ram do u have?its normal to slow ur pc down…vrdb creates backups of some important system files…it needs a lot of ram to run…select the option “generate vrdb when my pc is idle”…then it will create vrdb only when u do nothing on the pc
2gb and over 1gb free when i start it
ok…(i just wanted to check if it was a ram problem)…but as i know its normal slowing ur pc down…so calk down…go for a glass of water and leave vrdb do its job… 
I don’t know how you have set the VRDB to generate manually as there is no option to do that. I prefer to Generate mine manually but you can’t permanently set it up for that you have to select one of the other options, like generate when screen-saver is on, etc.
This is what I do, because I don’t use a screen-saver it will never run so I do a Generate Now every three weeks (21 days, which is the default for any of the auto creations). This works well for me and takes about 9-10 minutes, obviously I have nothing else running at the time.
Open Task Manager before doing the Generate Now and see what is using CPU %. So if you are going to do a manual generation don’t initiate it when you want to do something else, set it off and go for a coffee.
The VRDB data are stored in \Data\Integ\avast.int file.
Which is it size in your computer?
VRDB scans all the local hard disks for executable files and stores some info about them. VRDB is not a backup system, the stored information is very small (not the whole files). Besides, only Win32 executables are processed. So its size and the computer usage depends on how many files do you have in your computer and how many executables files are among them.