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 for the business solutions tested.

The stand-out business products are from Bitdefender, Trend Micro and Kaspersky, with F-Secure not far behind. Bitdefender did not received a 100% score for detection, but it was very close. Trend Micro, Kaspersky and F-Secure fell short in system performance impact, but not by much.

Here are the consumer products:

Bitdefender and Kaspersky get perfect scores, followed by Avira, F-Secure, Qihoo and G Data. Many products get a 6 in usability but are otherwise unremarkable or poor, including Kingsoft which gets a 0 on performance and 3.5 on protection. Nine products got a 6 on protection, the most important category, but some of them affect system performance negatively.

The two graphs below show the percentage of malware blocked by each product in December testing.