It has been said that Firefox 6 will perform better than previous version because it compiles with a newer version of GCC, version 4.5, and aggressive optimization.
When I updated to Firefox 6 in Natty I read the changelog and wondered whether Firefox 6 really would perform better than previous version in Ubuntu because one item in the changelog read (the changelog can be read via apt-get changelog firefox):
Unconditionally build with
--disable-elf-hack. It's basically a noop
on Ubuntu, as we don't get any of the nice space saving and startup
time improvements that upstream builds get with it. Enabling it is
problematic (it fails to build on all architectures in Ubuntu from
Firefox 7 onwards, and is already problematic on armel when building
on older Ubuntu versions)
What does this mean? Does it mean that Firefox 6 performance worse in Ubuntu than upstream?
Best Answer
See here for an explanation of the term "elf-hack". It's basically a compile-time linker optimisation.
In the last blog post from that link, JavaScript performance on the dromaeo benchmark is shown to be 0.6% better when firefox is compiled with the elf-hack.
So no, you won't notice any difference in regular use. Improvements in gcc will probably allow use of the 'elf-hack' in 11.10+ anyway.