Computer people: advice on virus checker

[strange_complex]

This is one for my computery friends:

I use an AVG virus checker, which I update once a week and which runs automatically once a day. I've been used to it taking about 20 minutes to run its daily test (of the whole C drive), or more if I am using my computer at the same time.

However, for the last couple of days it has suddenly been taking only about 10 minutes to run the same test. Nothing significant has changed about my C drive, so why might this be? And should I be worried: could it means there are parts of my C drive which now aren't being checked for some reason?

Everything else seems to be in full health, by the way.

Hope someone can help!

Comments

[neilh.livejournal.com]

You can easily calculate the theoretical lower limit on the time to scan a disk, which depends on the size of disk, how many files need to be checked, how much checking needs to be done, how fast your computer can talk to the disk, etc. There are many different ways to do things like virus scans, choosing which is the most efficient depends on the system structure.

However, what people forget is that the way to prevent viruses entering a system is to prevent them being *written* to the disk, rather than prevent them being *read* from the disk, that way there is no chance they'll infect you. If that were possible, virus scanning of this nature would be unnecessary.