meh.rb

#!/usr/bin/env ruby

require 'benchmark/ips'

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

def squiggly
  CALLER.each { |x| x =~ REGEX }
end

Benchmark.ips do |x|
  x.report("constant") { constant_regex }
  x.report("literal") { literal_regex }
  x.report("squiggly") { squiggly }
  x.compare!
end

__END__
Calculating -------------------------------------
            constant   136.776k i/100ms
             literal   139.374k i/100ms
            squiggly   138.983k i/100ms
-------------------------------------------------
            constant      6.643M (± 5.6%) i/s -     33.237M
             literal      6.529M (± 7.3%) i/s -     32.474M
            squiggly      6.502M (± 5.6%) i/s -     32.383M

Comparison:
            constant:  6642507.7 i/s
             literal:  6529384.0 i/s - 1.02x slower
            squiggly:  6501559.2 i/s - 1.02x slower