require 'benchmark'

TIMES = 1_000_000

r = /regexp/
s = "regexp"

Benchmark.bmbm do |x|
  x.report("r =~ s") do
    TIMES.times { r =~ s }
  end

  x.report("s =~ r") do
    TIMES.times { s =~ r }
  end
  
  x.report("r.match(s)") do
    TIMES.times { r.match(s) }
  end

  x.report("s.match(r)") do
    TIMES.times { s.match(r) }
  end
end

# Rehearsal ----------------------------------------------
# r =~ s       1.210000   0.000000   1.210000 (  1.207980)
# s =~ r       1.420000   0.010000   1.430000 (  1.428233)
# r.match(s)   2.560000   0.000000   2.560000 (  2.568816)
# s.match(r)   2.960000   0.000000   2.960000 (  2.961407)
# ------------------------------------- total: 8.160000sec

#                  user     system      total        real
# r =~ s       1.190000   0.010000   1.200000 (  1.193561)
# s =~ r       1.220000   0.000000   1.220000 (  1.218504)
# r.match(s)   2.780000   0.000000   2.780000 (  2.789282)
# s.match(r)   2.640000   0.000000   2.640000 (  2.646546)