Gentoo Optimizations Benchmarked (Linux Magazine)

Also, both Java and Emacs's problem is that they are insufficiently
integrated into the rest of the system: they're in their own little worlds
and barely realise that Unix is out there. So removing them is relatively
trivial. (Emacs in particular. There are elisp packages that depend on it,
but fundamentally it's for users to interact with, so it's not as if
removing it should lead to half your desktop being zapped because some
critical library depended on Emacs...)