Plus falcon patches? Here's a ruby-build formula for that:

    $ cat share/ruby-build/1.9.3-p125-falcon
    ## Hat tip to @burkelibbey and @metaskills - who did all the real work
    
    build_package_combined_patch() {
      local package_name="$1"
    
      {
        curl https://github.com/ruby/ruby/pull/47.diff | git apply
        curl https://raw.github.com/gist/1859082/performance_and_backport_gc.patch | patch -p1
        autoconf
        ./configure --prefix="$PREFIX_PATH" $CONFIGURE_OPTS
        make -j 8
        make install
      } >&4 2>&1
    
    }
    
    CC=$(which clang) install_package "yaml-0.1.4" "http://pyyaml.org/download/libyaml/yaml-0.1.4.tar.gz"
    CC=$(which clang) install_package "ruby-1.9.3-p125" "http://ftp.ruby-lang.org/pub/ruby/1.9/ruby-1.9.3-p125.tar.gz" combined_patch

There's this gist which combines all the patches and has you install a 1.9.3-p125-perf via rbenv: https://gist.github.com/2113359

Been using it at work for local dev and in production. Feels good, man.