`ruby bench.rb`

benchmark_spell_checker.rb

require 'benchmark_driver'

Benchmark.driver do |x|
  x.prelude <<~RUBY
    METHODS = ''.methods
    INPUT   = 'start_with?'

    spell_checker = DidYouMean::SpellChecker.new(dictionary: METHODS)
  RUBY

  x.report 'spell check', %{ spell_checker.correct(INPUT) }
  x.loop_count 10_000

  x.verbose
  x.rbenv(
    '2.3.6',
    '2.4.3',
    '2.5.0',
    '2.6.0-dev',
    '2.6.0-dev,--jit',
  )
end

results.txt

2.3.6: ruby 2.3.6p384 (2017-12-14 revision 61254) [x86_64-darwin17]
2.4.3: ruby 2.4.3p205 (2017-12-14 revision 61247) [x86_64-darwin17]
2.5.0: ruby 2.5.0p0 (2017-12-25 revision 61468) [x86_64-darwin17]
2.6.0-dev: ruby 2.6.0dev (2018-03-07 trunk 62693) [x86_64-darwin17]
2.6.0-dev,--jit: ruby 2.6.0dev (2018-03-07 trunk 62693) +JIT [x86_64-darwin17]
Calculating -------------------------------------
                          2.3.6       2.4.3       2.5.0   2.6.0-dev  2.6.0-dev,--jit
         spell check    962.002     920.626     817.009     838.779          630.131 i/s -     10.000k times in 10.394994s 10.862173s 12.239773s 11.922096s 15.869706s

Comparison:
                      spell check
               2.3.6:       962.0 i/s
               2.4.3:       920.6 i/s - 1.04x  slower
           2.6.0-dev:       838.8 i/s - 1.15x  slower
               2.5.0:       817.0 i/s - 1.18x  slower
     2.6.0-dev,--jit:       630.1 i/s - 1.53x  slower