AVG Antivirus Free Edition is the second antivirus I have installed on my computers and I have been using it for years. It has many features beyond its computer scanning ability, such as an E-mail scanner, web browsing shield, and even a tool for protecting your identity. That is all I am going to say about those features though, because the focus of this article is the computer scanner.
The scanner itself is quite capable and has a good record for catching zero-day threats, as well as older, identified pieces of malware. Considering it is free, it offers a pretty good package.
The scanner has many options including if it should look for tracking cookies, scan inside archives, and use heuristics to catch malware it cannot explicitly identify. Also you can set the priority of the scan process. For my tests I set it to high, allowing it to take what resources it needs from the system. Also, it is set to scan everything except for tracking cookies. (I have had issues years ago with cookies being caught and quarantined which are legitimately on my computer, so I do not scan for them. Instead I regularly remove all other cookies.)
Despite virtually all of the options being enabled, the scan still completes very quickly, taking just thirty three minutes. Looking at the resource use for my computer is actually somewhat interesting for AVG (but not the most interesting, as we shall see later). The start of the scan launches the CPU usage from around 10% up to 80%, before dropping to around 50%, ultimately returning to 80%. The memory usage also increases with the start of the scan, and then remains stable, so it is not very interesting. The disk transfers however are a different story. At the beginning of the scan it spikes quite high, and continues to dance around in the hundreds. However, once the CPU usage returns to 80%, the transfers almost completely drop off. Exactly why this happens is hard to tell, unless during that point of the scan AVG is looking at the already running processes, which would be in the memory and not on the disk. AVG does tell you what it is scanning while it is scanning, but I have no ability to directly connect that to the resource graph.
When completed, AVG presents you with a decent amount of information, including how long the scan took, how many objects is scanned, and the kind of scan it ran (in this case a whole computer scan). This information can be exported if you wish, but you are also able to view it later by visiting 'Reports.'
Overall, AVG offers a pretty good package with a strong scanner and multiple features. Its scans do seem to hog some resources, but that is the price you pay for speed. If that is a problem for you though, try playing with the priority setting or set it to scan when you are not using your computer.