Let me give you a quick fact about firefox first. >>Source
Firefox 3 Reaches 20 Million downloads in 7 Days, Opera - 4.5 Million Downloads in 5 Days
Open Firefox 3, Hit Ctrl+T and type “about:config”
1. Disable Extension Compatibility Checks
extensions.checkCompatibility = False
extensions.checkUpdateSecurity = False
2. Location Bar (Set number Auto Complete URL at Address Bar)
This is good for trimming down the huge auto complete bar, the default is 12
browser.urlbar.maxRichResults = #
