After I switched over to Firefox 3, I noticed that my Firefox used to freeze whenever I was downloading or to be more precise whenever a huge download finished. After few spending some time with the task manager and Google, I came to find that the culprit was the built-in feature of Firefox which scanned the downloads using the already installed anti-virus application in my system. Even though this feature is a good one, in my humble opinion its a drag for somebody who downloads in and out daily. It could be useful feature for a novice or my grandma if she ever wanted to use a computer but not certainly to me. I believe any person who spends more than an hour over the Internet daily would be sensible enough to have a anti-virus application running and update it frequently.  Your own anti-virus application should be able to take care of it instead of the browser taking the load.

So after spending some time with Google, I got lead to gHacks who had a detailed article on it. So here is how you disable this feature, type “about:config” in your Firefox’s address bar and run a search filter for browser.download.manager.scanWhenDone and change the parameter value to false which will disable the automatic scanning.

via [gHacks]