bench.rb

require 'benchmark'

  
  
20.times do
  p("%0.6f" % Benchmark.realtime {
      File.open('A.txt').readlines do |line|
        10.times do
          line[5]
          line[10]
          line[20]
          line[40]
          line[60]
        end
      end
  })
end

result.txt

jruby -Xcompile.invokedynamic gets_bench.rb
"0.757427"
"0.706870"
"0.775262"
"0.752200"
"0.638191"
"0.697848"
"0.840295"
"0.718880"
"0.775943"
"0.751087"
"0.861543"
"0.793738"
"0.731502"
"0.467162"
"0.724081"
"0.701253"
"0.768865"
"0.769979"
"0.662032"
"0.466345"

AFTER:

jruby -Xcompile.invokedynamic gets_bench.rb
"0.708550"
"0.586651"
"0.624988"
"0.587505"
"0.503620"
"0.515223"
"0.510485"
"0.765675"
"0.599085"
"0.606644"
"0.573161"
"0.413883"
"0.561218"
"0.597783"
"0.581685"
"0.576364"
"0.595542"
"0.340622"
"0.658417"
"0.704782"