Uhu! Pelo menos isso!

O Leopard está rodando mais rápido nos seguintes Macs:
- G4
- G5
- Core 2 Duo

The PowerPC instruction set was designed with a 64-bit implementation in mind; its "transition" to 64-bit was really nonexistent. The x86 instruction set, on the other hand, was created in the 16-bit era and has accumulated quite a bit of cruft going from 16-bit to 32-bit. Some of that cruft was wisely abandoned during the transition from 32-bit to 64-bit. Applications compiled for x86_64 don't just get larger registers, they get more registers, plus a more modern calling convention and more addressing modes.

Every 32-bit x86 application can benefit from these changes, it's just a question of how significant that benefit will be. This is not true of PowerPC applications, which get the added memory and cache pressure of 64-bit register sizes without any of Intel's cruft-abandoning benefits.

I say "x86 application" and "PowerPC application," but of course Leopard, like Tiger, supports what Apple calls Universal Binaries. These are single executable files that contain code for all supported architectures: 32-bit Power PC, 64-bit PowerPC, 32-bit x86, and 64-bit x86_64. Here's an example from Leopard.

% cd /Developer/Applications/Xcode.app/Contents/MacOS
% file Xcode
Xcode (for architecture ppc7400): Mach-O executable ppc
Xcode (for architecture ppc64): Mach-O 64-bit executable ppc64
Xcode (for architecture i386): Mach-O executable i386
Xcode (for architecture x86_64): Mach-O 64-bit executable x86_64