The latest incarnation of Norton AntiVirus installs quickly, then immediately begins to monitor the files you access, your instant messaging traffic, and any email attachments you receive, detecting and blocking malware before it can cause any harm.
On-demand scans use information on a file's "reputation" to improve performance. That is, if a file is flagged as trustworthy (it's been around for a while, many Norton users have a copy, there are no problems) then the program won't waste time scanning it repeatedly: once will do. This allows Norton Antivirus 2011 to skip a large number of files - 45% of those on our test PC - and makes for much faster scans.
The new Reputation Scan gives you access to the same information, clearly highlighting programs and files that are regarded as untrustworthy. If you've become infected by some brand new threat that hasn't been recognised yet then this could help you identify the culprit.
And Norton AntiVirus 2011 also now integrates with Norton Safe Web on Facebook, which scans your wall looking for shared links that point to phishing sites, known malware sources, or other unpleasant places.
All this functionality doesn't slow you down, however. When idle the program uses around 20MB of RAM, rising to around 100MB during a scan, and even at its peak barely reached 10% CPU usage on our test PC: we could continue browsing and working while scans ran in the background.
If you have problems, though, the new Performance tool may help. This tracks how your applications use CPU time, RAM and your hard drive, alerting you to any resource hogs. If you've noticed your PC has been slow recently, switch to the CPU report, for instance, highlight a recent moment of peak use and you'll be told which programs were most responsible, very useful when you're trying to improve system speeds.
What you won't get here are a firewall, spam filter or antiphishing protection. If that's a problem, take a look at Norton Internet Security 2011, a complete security suite that includes these features and adds some extras of its own.
Norton AntiVirus 2011 v18.6 contains many changes and fixes from the previous version. Some of these changes include Firefox 4 support, TidSrv detection, improved activation process, IE9 plugin support and compatibility issues.