I have a benchmark that exercises the "Matrix" library. I just ran it on
my 933 MHz Pentium III Coppermine and here is the log file:

-------------------------------------------------------------------
# capture original path
ORIGPATH=$PATH
unset RUBYOPT

# run benchmark with "stock" Ruby
ruby -v MatrixBenchmark.rb 256 nomathn
ruby 1.8.5 (2006-06-22) [i686-linux]
Matrix of dimension 256 times its inverse = identity?true
195.240000   0.010000 195.250000 (195.263929)
ruby -v MatrixBenchmark.rb 256
ruby 1.8.5 (2006-06-22) [i686-linux]
/usr/lib/ruby/1.8/mathn.rb:110: warning: discarding old /
/usr/lib/ruby/1.8/mathn.rb:114: warning: discarding old /
/usr/lib/ruby/1.8/mathn.rb:120: warning: method redefined; discarding
old inspect
/usr/lib/ruby/1.8/mathn.rb:233: warning: method redefined; discarding
old sqrt
Matrix of dimension 256 times its inverse = identity?true
202.170000   0.010000 202.180000 (202.196910)

# run with profiling Ruby
export PATH=/home/profiling-ruby/bin/:$ORIGPATH
ruby -v MatrixBenchmark.rb 256 nomathn
ruby 1.8.5 (2006-08-18) [i686-linux]
Matrix of dimension 256 times its inverse = identity?true
596.660000   0.000000 596.660000 (596.710885)
ruby -v MatrixBenchmark.rb 256
ruby 1.8.5 (2006-08-18) [i686-linux]
/home/profiling-ruby/lib/ruby/1.8/mathn.rb:110: warning: discarding old /
/home/profiling-ruby/lib/ruby/1.8/mathn.rb:114: warning: discarding old /
/home/profiling-ruby/lib/ruby/1.8/mathn.rb:120: warning: method
redefined; discarding old inspect
/home/profiling-ruby/lib/ruby/1.8/mathn.rb:233: warning: method
redefined; discarding old sqrt
Matrix of dimension 256 times its inverse = identity?true
613.620000   0.000000 613.620000 (613.668332)

# make the profile and annotated source listing
gprof `which ruby` > profile.txt
which ruby
gprof -A `which ruby` > source.txt
which ruby

# run benchmark with YARV
export PATH=/home/yarv-ruby/bin/:$ORIGPATH
ruby -v MatrixBenchmark.rb 256 nomathn
ruby 2.0.0 (Base: Ruby 1.9.0 2006-04-08) [i686-linux]
YARVCore 0.4.1 Rev: 519 (2006-07-12) [opts: [direct threaded code]
[inline method cache] ]
Matrix of dimension 256 times its inverse = identity?true
1422.360000   0.110000 1422.470000 (1422.583232)
ruby -v MatrixBenchmark.rb 256
ruby 2.0.0 (Base: Ruby 1.9.0 2006-04-08) [i686-linux]
YARVCore 0.4.1 Rev: 519 (2006-07-12) [opts: [direct threaded code]
[inline method cache] ]
/home/yarv-ruby/lib/ruby/2.0/mathn.rb:19:in `remove_method': method
`gcd2' not defined in Integer (NameError)
        from /home/yarv-ruby/lib/ruby/2.0/mathn.rb:19:in `<class:Integer>'
        from /home/yarv-ruby/lib/ruby/2.0/mathn.rb:17:in `<top (required)>'
        from MatrixBenchmark.rb:2:in `require'
        from MatrixBenchmark.rb:2:in `<main>'

-------------------------------------------------------------------
The key here is that YARV takes 1422.6 seconds to complete this test,
and the "stock" Ruby 1.8.5 takes only 195.3 seconds.

For more details, this is all on my RubyForge site at

http://rubyforge.org/cgi-bin/viewvc.cgi/MatrixBenchmark/?root=cougar

I'll probably try the profiling on the YARV benchmark tomorrow.

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