hash.rb

require 'benchmark'

TIMES = 5000000

Benchmark.bmbm(40) do |x|
  x.report('hoge[:fuga] = foo') do
    hoge = {}
    foo = :foo
    TIMES.times do
      hoge[:fuga] = foo
    end
  end

  x.report('hoge.update(:fuga => foo)') do
    hoge = {}
    foo = :foo
    TIMES.times do
      hoge.update(:fuga => foo)
    end
  end
end

output

% ruby -v hash.rb
ruby 2.0.0dev (2011-10-21 trunk 33499) [x86_64-linux]
                                               user     system      total        real
hoge[:fuga] = foo                          0.750000   0.000000   0.750000 (  0.754151)
hoge.update(:fuga => foo)                  2.740000   0.000000   2.740000 (  2.754672)
% ruby187 -v hash.rb
ruby 1.8.7 (2011-06-30 patchlevel 352) [x86_64-linux]
                                              user     system      total        real
hoge[:fuga] = foo                         1.180000   0.000000   1.180000 (  1.188576)
hoge.update(:fuga => foo)                 2.750000   0.000000   2.750000 (  2.759662)
% JAVA_HOME=/home/nahi/java/jdk1.7.0_b08 jruby -v hash.rb                                         
jruby 1.7.0.dev (ruby-1.8.7-p330) (2011-10-26 1c99cf2) (Java HotSpot(TM) 64-Bit Server VM 1.7.0_02-ea) [linux-amd64-java]
                                              user     system      total        real
hoge[:fuga] = foo                         0.648000   0.000000   0.648000 (  0.606000)
hoge.update(:fuga => foo)                 1.156000   0.000000   1.156000 (  1.156000)
% JAVA_HOME=/home/nahi/java/jdk1.6.0_26 jruby -v hash.rb
jruby 1.7.0.dev (ruby-1.8.7-p330) (2011-10-26 1c99cf2) (Java HotSpot(TM) 64-Bit Server VM 1.6.0_26) [linux-amd64-java]
                                              user     system      total        real
hoge[:fuga] = foo                         0.739000   0.000000   0.739000 (  0.700000)
hoge.update(:fuga => foo)                 1.432000   0.000000   1.432000 (  1.432000)
% rbx -v hash.rb   
rubinius 2.0.0dev (1.8.7 77af8dea yyyy-mm-dd JI) [x86_64-unknown-linux-gnu]
                                              user     system      total        real
hoge[:fuga] = foo                         1.036065   0.000000   1.036065 (  1.048594)
hoge.update(:fuga => foo)                11.948746   0.008001  11.956747 ( 12.193963)
% rbx124 -v hash.rb
rubinius 1.2.4 (1.8.7 release 2011-07-05 JI) [x86_64-unknown-linux-gnu]
                                              user     system      total        real
hoge[:fuga] = foo                         1.184074   0.004001   1.188075 (  1.198592)
hoge.update(:fuga => foo)                10.312644   0.024001  10.336645 ( 10.487060)