VirusBarrier X5 (version 10.5.2) bills itself as simple, fast, and non-intrusive, and it certainly lives up that billing, with the notable exception of the program’s nonstandard interface. This antivirus program scans files very quickly and, perhaps more important, with very little impact on your Mac’s resources. VirusBarrier has two ways of scanning your Mac: real-time and manual. The real-time scanner constantly scans your Mac’s files in the background, but it didn’t slow down my test Mac (a 2.16GHz Intel Core Duo MacBook Pro) in the slightest. The manual scan is a little more resource intensive.