I have switched from Norton to Kaspersky Antivirus for several reasons. Kaspersky is better in terms of (1) Frequent updates (2) Better detection rate (3) Using lesser CPU resources (latest version : 7.0.125)

However, I can no longer use Agnitum Outpost Firewall due to its frequent BSOD. I read about this at many forums and there are just too many answers to this problem and none works for me. Later, I uninstalled Outpost Firewall and voila, no more BSOD. Oh god, how can I leave my computer like that without a firewall? So, I upgraded to Kaspersky Internet Security and everything works out well. The only setback in KIS is the missing “Allow once” & “Block Once” which I use very frequent when Outpost is installed. KIS does have these 2 options but you need extra click to get them which I feel not so user-friendly.

To my surprise, KIS 7.0.125 uses very less resources (less than 10MB) with both firewall and antivirus features. Well, actually there are more features in KIS but I don’t use them. It includes Spyware Protection, Spam Filter (I’m using Mailwasher & Gmail), Web Antivirus (I have Noscript) & Popup Filter (Firefox does this better). One powerful feature that I like the most is the iSwift & iChecker Technology.

As documented in Kaspersky website:

iChecker operating principles
During the first scan the check sum of an object is saved. Check sum is a unique digital signature of an object (file) that allows identifying this object (file). Check sum changes every time the object is modified. This information is saved in a special table. During the next scan of an object the previous and current check sums are compared. If the check sum is different it means the object was changed and it should be scanned for a malicious code once again, if the check sum is the same, the object was not changed and therefore it is not scanned.

iSwift operating principles
The technology has been developed for NTFS file system. In this system NTFS-identifier is given to each object. This NTFS-identifier is compared with the values in the special iSwift database. If the values do not coincide with the NTFS-identifier then the object is scanned or rescanned, if it has been changed.

This can definitely helps speeding up your subsequent scanning. Because of this technology, I set a schedule scan to weekly where previously in Norton, I set it to quarterly.