forked from: forked from: BitmapDataで配列に格納すると高速化するよ

So basically the original Flash rendered each arrow as an individual bitmap, but instead why not
blit all the arrows onto one single bitmap? I thought it was weird that you'd have a lot of 
individual bitmaps, and for one second I thought that might actually be faster, thinking Flash
would natively render each bitmap instead of using Flash's copyPixels, but apparently
copyPixels IS faster.

Thanks to the following forkers and the original coder for making me realise this. :-)
- Johannes, funbyjohn.com

矢印がいっぱいなんだけど、高速なデモ
画質はディフォルトの StageQuality.HIGH で
矢印 1000個
@author Yasu