VirusBarrier is a good program, working as it says. But some functions may cause slow performance of Mac, so I just excluded some unnecessary functions, like TimeMachine. Another good thing of this program is it updates regularly to keep up with the latest threats. My Mac is absolutely safe with it.
The program has a pretty and clear UI, but it crashes too much and took too many system resources, largely slowing down the speed of my Mac. I had to uninstall it and move to AVG, free and well.
It's not easy for Mac to get infected by viruses, but a good antivirus program is still necessary, at least for me. VirusBarrier is the best antivirus program for Mac I've tried.