I have just started using this, and am very impressed so far. After installing it and doing the required reboot, it is extremely light for me. It is having zero noticeable effect on system performance, which on my laptop is rare. At times after the reboot I have seen relatively high CPU use while it has been updating. But very surprisingly, it has not lead to a slowdown in performance. The initial update took a while to complete. Since it is takes place silently in the background, there was not way to check the progress. The HIPS is working quite well, and also when I visited a known questionable website, I immediately go a popup telling me the site was unsafe, but also giving me the option to whitelist it, in case I wanted to ignore the warning and still visit it. When I went to do a context menu scan of my downloads folder, I was recommended to have the definitions updated first due to them being updated. When I selected to do the update before scanning, the scan started as soon as the update was completed. I was concerned about the lack of an option to be prompted for what action to take when a threat is found. But when I did a scan nothing was dealt with automatically. When the scan was finished I was able to deal with the threats manually. This is good in my case, as I won't use antivirus software which automatically quarantines threats without asking first. When attempting to execute an infected file, once again you are prompted what action to take. If you want to run the file despite the warning you have the option to whitelist that specific file, or whitelist the threat so that anytime that same threat is encountered it will be ignore, rather than just the single instance of it. So far I am really liking this antivirus. There was a performance hit when running a scan, but otherwise it is very light so far. It is important to note that there are other antiviruses which I have found to be very light when first installing them, but after trialing them for a while have found periods where they cause noticeable slowdowns - even if only briefly. Time will tell how Ashampoo Antivirus fares, but I will post back here.