Independent test lab AV-Test has completed a series of tests for antivirus/anti-malware products on Windows 8 and 8.1.
They compared both business and consumer solutions. For each, they tested with the then-current version last November and December to increase confidence in the numbers. They compared the business solutions to Microsoft System Center Endpoint Protection and the consumer solutions to Microsoft Windows Defender.
For each, AV-Test generated scores for protection, performance and usability. Each score ranges from 0 to 6 and are added to make the Total score.
Protection is defined by how well they blocked known and unknown malware. Products with a score of 6 blocked 100 percent of malware or very close to it. Performance is a measure of the product's impact on the system speed, but AV-Test provides no details on how the numbers were calculated. Usability is a function of the number of false positive detections in various situations; "Usability" is perhaps not the right word for it, but it's a valuable metric nevertheless.
Below are the scores....
Read more at: Antivirus on Windows 8/8.1 compared | ZDNet