This is a guide for compiling firefox 1.5.* on Ubuntu Breezy 5.10.

 1. Install necessary development packages:{{{
  $ sudo apt-get install build-essential libgtk2.0-dev libidl-dev libxt-dev libgnomevfs2-dev
}}}

 1. Download and extract firefox source tar ball:{{{
  $ wget \
http://ftp.mozilla.org/pub/mozilla.org/firefox/releases/1.5.0.1/source/firefox-1.5.0.1-source.tar.bz2
  $ tar jxvf firefox-1.5.0.1-source.tar.bz2
  $ cd mozilla
}}}

 1. Create the .mozconfig file in the firefox source directory:{{{
  $ cat > .mozconfig <<EOF
. \$topsrcdir/browser/config/mozconfig

export MOZILLA_OFFICIAL=1
export BUILD_OFFICIAL=1
mk_add_options MOZILLA_OFFICIAL=1
mk_add_options BUILD_OFFICIAL=1
ac_add_options --enable-official-branding

mk_add_options MOZ_OBJDIR=@TOPSRCDIR@/firefox-bin

ac_add_options --enable-default-toolkit=gtk2
ac_add_options --enable-pango
ac_add_options --with-user-appdir=.mozilla
ac_add_options --with-system-png=/usr
ac_add_options --with-system-jpeg=/usr
ac_add_options --enable-postscript
ac_add_options --disable-installer
ac_add_options --disable-xprint
ac_add_options --enable-crypto
ac_add_options --enable-strip-libs
ac_add_options --enable-canvas
ac_add_options --enable-svg
ac_add_options --enable-svg-renderer=cairo
ac_add_options --enable-system-cairo
ac_add_options --enable-mathml
ac_add_options --disable-tests
ac_add_options --disable-gtktest
ac_add_options --disable-debug
ac_add_options --enable-xft
ac_add_options --enable-optimize="-O3 -march=pentium-m -mtune=pentium-m -pipe -ftracer -fomit-frame-pointer"
ac_add_options --with-system-zlib=/usr
ac_add_options --without-system-nspr
ac_add_options --enable-xinerama
ac_add_options --enable-extensions=default
ac_add_options --disable-pedantic
ac_add_options --disable-long-long-warning
ac_add_options --enable-single-profile
ac_add_options --disable-profilesharing
ac_add_options --enable-gnomevfs
ac_add_options --disable-updater
EOF
}}}
  '''Note:''' You may need to adapt the --enable-optimize gcc parameters to your own platform. Pay special attention to the "march" and "mtune" parameters. If they are speicified for the wrong architecture, you may not be able to compile Firefox. To see what architectures are available with gcc, type: {{{
man gcc
}}}
  and then navigate to the section titled "Intel 386 and AMD x86-64 Options." In this section is a list of supported architectures for the "march" and "mtune" options. Choose the option closest to your CPU.

 1. Build firefox:{{{
  $ make -f client.mk build
  $ make -C firefox-bin/browser/installer/
}}}

 1. Follow the instructions in FirefoxNewVersion to install your newly built firefox-1.5.*.tar.gz, which can be found in mozilla/firefox-bin/dist/.

== Third Party builds ==
If for some reason you do not want to go through the process of compiling Firefox but would like to enjoy the benefit of a gcc4 compiled build, you can visit the Mozillazine forum  [[http://forums.mozillazine.org/viewforum.php?f=42|Third Party/Unofficial Builds]] section to look for pre-compiled builds made by third parties. 

For example, in Ubuntu forum there is discussion on AthlonXP optimized gcc4 build such as [[http://www.ubuntuforums.org/showthread.php?t=142798|Swiftfox]].