The stated goals for Mac OS X 10.6 'Snow Leopard' have been on improving performance, efficiency, and lowering the overall memory footprint of this operating system. With these performance tuning efforts, Apple has dropped support for the older PowerPC-based Apple computers and are now focusing strictly on Intel-based hardware and optimizing for x86_64-capable processors. Snow Leopard brings full 64-bit support both in the kernel and for their user-space applications, except for a few that are not yet ported like iTunes and QuickTime. Lingering (itch) mac os. The 64-bit addressing support alone should yield a nice performance boost, but greater performance gains in Mac OS X 10.6 can to a large extent be attributed to Grand Central Dispatch (GCD) and OpenCL.
Apple's Grand Central Dispatch is designed to deliver better desktop performance through improving parallel programming on Mac OS X with multi-core processors by making it easier on developers and on the operating system by handling the thread management and ensuring all CPU jobs are distributed across the available computing cores. Xcode in Mac OS X 10.6 has also received more work to LLVM (the Low-Level Virtual Machine) and Clang, as an alternative to the GNU Compiler Collection.