Challenge: fastest program wins

Write a program in your language that
1.opens a file as arbitrary precision integer.
2.divides the number by 3.
3.stores the binary result in another file.

There would never be a shippable product.
Wrong, you'd just have to wait longer.

I also believe that optimization should be an integral part of the design process. If you're going to write code, then do as much as possible to get it right and optimized the first time before you write, otherwise you're just spending extra time rewriting shit.