Ruby 初心者スレッド Part 33

文字列をn文字ずつ＆1文字ずつに分割したいのですが
x = "ABCDEFGHIJKLMNOPQRSTUVWXY"
x = x.scan(/.{5}/)
x.collect!{|y|y.scan(/./)}
p x
=>[["A","B","C","D","E"],["F","G","H","I","J"],["K","L","M","N","O"],["P","Q","R","S","T"],["U","V","W","X","Y"]]
みたいに書くと都度、正規表現によるマッチが行われるので遅いです
もっと高速に実行する方法があったら教えてください。よろしくお願いします