I switched from Firefox 2 to Firefox 3 a few days ago and love the speed of the new version of Firefox. It's not a speed gain that's only appearing in benchmarks but one that every user will recognize as well. There was one minor incident though after upgrading to Firefox 3 that turned out to become a huge problem. Firefox 3 was frantically writing on my hard drive and raising cpu usage periodically which brought the browser to an complete halt in that time.
It usually lasted for 30-60 seconds and everything turned back to normal afterward. I first thought it had something to do with the Live Bookmarks and how Firefox was updating them but it turned out that this was not related. I read that the bookmarks would be saved in a database and not in an html file anymore which is why I though it could be the reason.
I eventually discovered a thread in the Ubuntu forums entitled Firefox 3 is eating my hard drive which lead to a bug report at the Mozilla website and a fix for Linux. My problem was that I was using Windows and not Linux and had the same symptoms.
The fix for Linux was to change the default value of the parameter Urlclassifier.updatecachemax from -1 to 104857600. The -1 value for the maximum cache size means unlimited and is the default value for all other operating systems while the value for Linux has been set to 104857600 which is 100 Megabyte.
I did change the value of Urlclassifier.updatecachemax from the default Windows value to the default Linux value and have not been experiencing any excessive cpu and hard disk usage since.
The question is: Was I the only one affected by this high cpu and hard disk usage ? What is your experience with Firefox 3 ?
The Brief Firefox extension, an add-on to view RSS Feeds in Firefox seems to have played a bigger role. After checking the profile directory I noticed regular updates to a 78 Megabyte file called Brief.sqlite which I identified as another reason for the excessive hard disk and cpu usage. I therefor decided to disable the add-on for now.
It still did not solve the problem fully. After exporting my Firefox Live Bookmarks and deleting them in Firefox I can finally say that I'm lag free.