gistfile1.txt

Calculating -------------------------------------
               #gsub     19583 i/100ms
              #gsub!     18808 i/100ms
-------------------------------------------------
               #gsub   299922.0 (±4.6%) i/s -    1507891 in   5.038274s
              #gsub!   281888.2 (±3.9%) i/s -    1410600 in   5.011569s

Comparison:
               #gsub:   299922.0 i/s
              #gsub!:   281888.2 i/s - 1.06x slower

gistfile2.rb

require 'benchmark/ips'

Benchmark.ips do |bench|
  bench.config(time: 5, warmup: 2)

  bench.report("#gsub") do
    unused = "literalstring".gsub(/era/,'o')
  end

  bench.report("#gsub!") do
    unused = "literalstring".gsub!(/era/,'o')
  end

  bench.compare!
end