Mac OS X 10.6 Snow Leopard review

Compared to its predecessor, Snow Leopard's release at the end of August was met with a muted reaction. It even arrived slightly ahead of schedule. So why wasn't there a bigger celebration?

That Apple hasn't adopted an entirely different cat for its marketing is a big clue. When you sit in front of Snow Leopard, you'll be hard pressed to tell the difference until you start poking around. And don't expect to find major new features on the level of Leopard's vaunted Time Machine, Tiger's Spotlight or even Panther's Exposé. The big changes are behind the scenes. With that in mind, why should you bother upgrading at all?

First of all, Snow Leopard needs an Intel Mac for good reason. The system has been ripped apart and put back together to make it work better with multi-core processors, and in the process Apple has thrown away years' worth of accumulated code written for PowerPC processors. The system takes up a bit less space, but it's more about making the best of hardware that's available and forthcoming. If you've already made the leap to Intel, you won't have to upgrade again to start reaping the benefits.

We installed Snow Leopard on a 15-month old iMac that had been used almost daily during that time, over which it had accumulated a large number of applications, documents and other files. It didn't take long to realise that it was no longer prone to the lengthy shutdown times of more than a minute that it often exhibited under Leopard. On this system, we recouped just over 13GB of disk space, though Apple reckons the typical difference is about 7GB.

Bear in mind that it's only the built-in applications that are leaner. Snow Leopard doesn't strip out PowerPC code from other software, though third-party tools accommodate that. The Rosetta translation layer is still available as an optional install, in case some of your applications still haven't been updated.

This final, concerted push towards Intel has allowed Apple to focus on several technological innovations. First up, Apple claims that 90% of the system has been reengineered, and many built-in applications are now 64-bit. That's not such a big deal for iCal and Address Book, but programs that demand power and memory will be able to get it, at least once they've been given the same treatment. Peripheral drivers and browser plug-ins that run in 32-bit mode should still run fine if you set the parent application to match, and thankfully System Preferences automatically restarts itself, so you can get at older preference panes.

Next up is Grand Central Dispatch, whose purpose is to spread an application's work more efficiently between your Mac's multiple cores. Right now, only Mac Pro and Xserve have more than two cores per processor, and we'll only see how well Apple has done its job with respect to scalability as time progresses. All of this takes place out of sight, so it's nothing that you need to worry about. It's more a concern for developers to whom Apple has provided new support tools.

Similarly, you won't lay your eyes upon OpenCL, which eases the CPU's workload by tapping into the graphics processor's idle time. It's relevant to fewer existing Macs because it doesn't work with every graphics card. MacBook Pros dating back to 2007 are okay, but some Mac Pro cards offered in early 2008 aren't. You can forget about it running on an Intel GMA processor, but any Mac with a GeForce 9400M or better is good to go. That includes the latest Mac mini, so you won't feel shortchanged when upgrading on a budget.