gistfile1.txt

tango:src/rbx[hydra]% rbx -Xgc.large_object=5000 reverse.rb 4900          
      user     system      total        real
Reversing string 4900 long  3.644228   0.004000   3.648228 (  3.751245)

tango:src/rbx[hydra]% rbx -Xgc.large_object=2700 reverse.rb 2665          
      user     system      total        real  
Reversing string 2665 long 13.372836   0.028001  13.400837 ( 13.470050)

gistfile2.rb

require 'benchmark'

def do_reverse(r)
  s = 'a' * r

  1000000.times { s.reverse }
end

r = ARGV.shift.to_i

Benchmark.bm do |b|
  b.report "Reversing string #{r} long" do
    do_reverse(r)
  end
end