I ran BitDefender and ClamAV first, both reeturned 3 viruses each which were quarantined, Taking between an hour to 3 each to run on my new iMac. Then I ran Dr. Web, and after 2 full days and nights of running it still was not finished the initial scan, having found 274 viruses (which I doubt is correct) up until that time. I finally quit the App, but the next time I started my iMac it launched again ready to start the scan over. Then I checked and found that the default checks for virus updates every 30 minutes, one of the reasons this is the slowest Anti-Virus App Ive ever witnessed. I have now deleted the App because it slowed my iMac to a crawl when it was running as well. .