$ ruby -v
ruby 2.3.1p112 (2016-04-26 revision 54768) [x86_64-darwin15]
$ ruby ruby_fast_choose_article.rb
Warming up --------------------------------------
String#=~ 98.496k i/100ms
String#start_with? 148.433k i/100ms
Calculating -------------------------------------
String#=~ 1.292M (± 2.7%) i/s - 6.501M in 5.034701s
String#start_with? 2.267M (± 2.4%) i/s - 11.429M in 5.044754s
Comparison:
String#start_with?: 2266957.7 i/s
String#=~: 1292136.3 i/s - 1.75x slower