literal_vs_constant_regex.rb

require 'benchmark'

CALLER = caller
REGEX = /(\/app\/(controllers|models|views)\/.+)/.freeze

def constant_regex
  CALLER.each { |x| x.match(REGEX) }
end

def literal_regex
  CALLER.each { |x| x.match(/(\/app\/(controllers|models|views)\/.+)/) }
end

N = 10_000_000

Benchmark.bm do |x|
  x.report("constant") { N.times { constant_regex } }
  x.report("literal") { N.times { literal_regex } }
end

#           user     system      total        real
# constant  0.940000   0.000000   0.940000 (  0.943816)
# literal   0.960000   0.000000   0.960000 (  0.968538)