Paring an array of strings down to just those matching a given pattern is way faster with Array#grep

array_grep.rb

# big_array has over 120,000 strings in it

def select_search(q)
  big_array.select do |s|
     s =~ /^#{Regexp.esecap(q)}/
  end
end

def grep_search(q)
  big_array.grep( /^#{Regexp.escape(q)}/ )
end