Any thoughts on i386 vs Amd64?

I just purchased another computer (The exact same computer that I'm
using now) Both computers run amd64-bit/CPU. Both computers are running
FreeBSD, the difference is that I installed FBSD-i386 on 64-bits
due to Nvidia drivers etc.

On the new computer I went with FBSD-amd64. I have maple installed on
both pc's.

I ran some computational linear algebra pbs, I WAS SHOCKED!!
Computations that took an hour on i386 (running the exact same
hardware) took 27 minutes on amd64-bits.

What about you guys, any benchmarks/thoughts to share?