He's right about needing a fast Math::BigInt library, the perl-only versions are too slow. It's been about 2 hrs and no results yet.
If you want really fast code with which to manipulate large integers then I recommend getting Crandall's giants.c and giants.h C code from Perfectly Scientific. This code is used as a base library for the factorization of large composite numbers.
You will, of course, need a C compiler. If you want to actually hack the library you will need some patience as there is very little documentation and the code is very terse. Using the library functions though is relatively easy to do.
"The doktor is in."