Upgrade to Go Faster?
Most of the time, software upgrades add new features at the expense of speed. (Imagine if Microsoft Word 2008 was as efficient on my 1.86GHz Intel processor as Word 5.1 was on my Mac SE's 8MHz processor--I could finish National Novel Writing Month in three hours!) But since Snow Leopard was announced, Apple has repeatedly said that this update is about not just fixing bugs and making tweaks, but improving performance.
When it comes to speed, there are actually two Snow Leopard stories. One is about the speed boosts the system provides today. The other is about the potential speed boosts that users may see in the future, as both software and hardware continue to evolve.
Let's start with the present. Macworld Lab compared Leopard to Snow Leopard in 16 different speed tests on three different systems. On half of our tests, Snow Leopard showed definite speed improvements when compared to Leopard.
My subjective experience using Snow Leopard for several weeks is essentially consistent with those lab results. Some tasks simply feel faster in Snow Leopard than in Leopard, while others seem no different at all. In general, I think most users will find that Snow Leopard feels faster and runs smoother than its predecessor.
In the future, however, the software than runs on Snow Leopard has the potential to become dramatically faster. That's because Apple has provided two technologies for software developers that should enable them to give their apps a speed boost, provided they put in the work to take advantage of the new technologies.
The first technology, Grand Central Dispatch, helps programmers split up their programs into smaller chunks so that they can more effectively use the power of computers with multiple processing cores. It's still quite a bit of work for programmers to break up tasks into chunks, but Apple says it hopes that developers will find the work a lot easier than it was before--and that the end result will be faster software, since every current Mac model has at least two processor cores.
The second technology, OpenCL, is a system programmers can use to take advantage of the massive amount of processing power locked up in a computer's graphics processor. By targeting certain tasks on the graphics processor, programmers can harness even more power to improve the speed of their programs.
The long-term direction of the computer industry is toward computers with many more processing cores and incredibly powerful (and increasingly flexible) graphics processors. Your current computer might only have a couple of cores and might not even have a snazzy graphics processor. (My MacBook Air certainly doesn't.) But by building Grand Central Dispatch and OpenCL into Snow Leopard, Apple is placing a bet on that future, and asking its community of third-party developers (as well as the developers of all the applications bundled with Snow Leopard) to embrace it. There will be small payoffs now, but next year's Macs will undoubtedly exploit these features to a much greater extent.
In truth, neither of these features is a reason to buy Snow Leopard today. But they will help make the next Mac you buy be much faster than it would have been otherwise.
And finally, a word about stability. Generally every major operating-system upgrade steps forward in terms of features and backward in terms of stability. Apple's engineers have had nearly two years to wring the bugs out of Leopard; the new features introduced in Snow Leopard will have no doubt introduced some new ones. But I'm happy to report that, in general, Snow Leopard seems as stable as it seems fast. Yes, I did see a few crashes from Safari, and I also experienced more crashes in Mail than I had experienced when using Leopard. Presumably Apple will address these sorts of bugs with forthcoming updates to Snow Leopard, but stability issues have never made me feel regret about switching from Leopard to Snow Leopard.
Macworld's Buying Advice
Snow Leopard is Apple's lowest-priced OS update in eight years. Granted, it's a collection of feature tweaks and upgrades, as well as under-the-hood modifications that might not pay off for users immediately. But the price of upgrading is so low that I've really got to recommend it for all but the most casual, low-impact Mac users. If you've got a 32-bit Intel Mac (that is, one powered by a Core Solo or Core Duo processor), the benefit of this upgrade will be a little less. But for most Mac users, especially the kind of person who reads a Web site devoted to the subject, the assorted benefits of Snow Leopard outweigh the price tag. I'd pay $30 just for the improved volume ejection, the ability to create services with Automator, and the improvements to the Dock and Exposé--though I admit I'd pay slightly more to not have the misguided QuickTime Player X as a part of the package. If you're a user who connects to an Exchange server every day, upgrading to Snow Leopard really is a no-brainer. For everyone else, maybe it's not quite a no-brainer--but it's awfully close. Snow Leopard is a great value, and any serious Mac user should upgrade now.
Jason Snell, Macworld's editorial director, has been writing in depth about Mac OS X since day one.