Basic Ruby 2.0 benchmarks calculating pi from gist [1]
$ ruby --version
ruby 1.9.3p385 (2013-02-06 revision 39114) [x86_64-darwin12.2.1]
$ time ruby pidigits.rb 10000 2>&1 > /dev/null
17.51s user 0.11s system 99% cpu 17.639 total
$ ruby --version
ruby 2.0.0p0 (2013-02-24 revision 39474) [x86_64-darwin12.2.1]
$ time ruby pidigits.rb 10000 2>&1 > /dev/null
4.64s user 0.27s system 99% cpu 4.927 total
That's a significant difference in speed. Going from 17.51 seconds to 4.64 seconds