Again Phoronix had tested the big U, now the rival is MacOS X. They used a MacMini and installed Ubuntu 32b and 64b with BootCamp.
Ok, some rounds Ubuntu won, like this:
but others MacOS X was the best:
Just one comment, remember than MacOS X is still in 32b, some parts are migrated to 64b but the kernel and base system is 32b native. Should MacOS X in 64b native be a big difference? Only the Snow Leopard knows and I predict: Yes.