After upgrading from Firefox 2 to Firefox 3, I noticed some strange behavior in terms of memory usage and, mainly, CPU usage.
My browsing habits cause open windows and tabs within windows to multiply in no time, so I expected some improvement by upgrading. Though memory consumption was slightly better, and hovering over the History menu item no longer freezes up the browser for several minutes, CPU hogging was worse than before the upgrade.
- in the URL field, type about:config
- locate the Urlclassifier.updatecachemax setting and set it to 104857600.
- locate the browser.cache.memory.enable setting and click to set it to false.
My Firefox ran smoother after restarting the browser.