In this momet i'm surfing on internet with Swiftfox.
Swiftfox is an optimized build of Firefox. Each x86 processor have his optimized package. For example i've tryed the athlon-xp build with this rendering test.
The obtained results are 7 seconds of rendering work with Swiftfox and 10 with Debian standard Firefox.
There's also an improvement in program's loading time.