regexp.rb

require 'benchmark'

TIMES = 1_000_000

Benchmark.bmbm() do |x|
  # note: this regexp will only be built once for all iterations
  x.report("literal regexp") do
    TIMES.times { /regexp/ }
  end

  x.report("new regexp from regexp") do
    TIMES.times { Regexp.new(/regexp/) }
  end
  
  x.report("new regexp from string") do
    TIMES.times { Regexp.new("regexp") }
  end
end

# Rehearsal ----------------------------------------------------------
# literal regexp           0.180000   0.000000   0.180000 (  0.188121)
# new regexp from regexp   6.690000   0.010000   6.700000 (  6.705013)
# new regexp from string   7.670000   0.010000   7.680000 (  7.672104)
# ------------------------------------------------ total: 14.560000sec

#                              user     system      total        real
# literal regexp           0.280000   0.000000   0.280000 (  0.277063)
# new regexp from regexp   6.830000   0.020000   6.850000 (  6.847951)
# new regexp from string   7.760000   0.010000   7.770000 (  7.767159)