I've been using the betas for several months on Vista Ultimate and really liked Avast 5. (I LOVE the GUI in particular). This release version (.377 now) is far more buggy than the beta versions I used.
I merely LOOK AT (not downloading anything) Firefox or Opera download tabs, Avast locks the CPU at 100% usage for at LEAST 3-5 MINUTES! Evidently, it thinks the LINKS on those tabs are actual files and it scans all of them. I have no intention of clearing the links as I use those links frequently as the fastest way to open to the file in the Downloaded Programs folder. Fx will clear them automatically after about three months anyway so they don't ever become a massive list. With Opera, I clear them when I get a long list but not until then. I have never had ANY other AV program treat those links as though they are the actual files! I set any AV I use to "scan all files" in real time and no other AV has caused a problem like this on my browser's download tabs.
When I download a file, even a very small one (75KB), Avast locks the CPU at 100% for 3-5 minutes also while it scans all those links and delays the download until it scans the links and this takes 3-5 minutes. I noticed this behavior with the latest beta builds but it was less dramatic and slowed downloads but wasn't locking the CPU for long periods until the release version.
The other irritating problem I have is that Avast cannot remember its settings. It remembers the ones that are not that important but it forgets the important settings as soon as I shut down the computer. When it was locking the CPU a little while ago, I tried to kill the process in Task Manager and was blocked! Now, the first thing I do with an AV with bad settings like Avast and Avira regarding protecting themselves (I will protect my AV in other ways thank you) is uncheck that setting. In Avast you have really hidden that setting but I found it and unchecked it. That setting should not exist as I need full control at all times over what processes are doing on my computer and if I need to kill one I should be able to do that. Layered security is essential. Use a classic HIPS to protect your AV from malware modifying its processes but don't let it protect itself as you can get into a terrible mess that way.
Anyhow, Avast had forgotten that setting. It forgets every time I shut the computer down. Plus, in this case, I had updated the version and that also makes Avast forget important settings. I didn't check that setting after updating although I checked the others and it had reverted all of them to the defaults that most Antivirus programs use because otherwise users without powerful computers complain about slowness. It also forgot my settings for Scan when writing, Advanced, and Actions and some others also.
Otherwise, it is performing well and as long as I don't shut the computer down so my settings are forgotten, or update the build (so the settings are forgotten), or download anything or look at my browsers download tabs (just surf) then everything is ok.
