Apple describes Snow Leopard as a top-to-bottom refinement of existing features. One major goal of those refinements: Improved performance.
Snow Leopard aims to run leaner and faster on current and recent Macs, in part by dropping support for legacy Power PC systems and focusing solely on Intel-powered Macs. And while some of Snow Leopard's potential performance gains won't show up until software developers optimize their applications for the new OS, others are apparent right now.
To check the performance benefits, we tested Snow Leopard on three different systems: a 20-inch iMac Core 2 Duo/2.66GHz ( Macworld rated 3.5 out of 5 mice ) with 2GB of RAM; a 3GHz Xeon 5300 eight-core Mac Pro with 4GB of RAM (this Mac Pro was released in April 2007); and a 15-inch MacBook Pro Core 2 Duo/2.8GHz ( Macworld rated 4 out of 5 mice ) with 4GB of RAM. The hard drives in each system were partitioned into two equal sizes, and we installed Leopard (OS 10.5.8) on one partition and Snow Leopard (OS 10.6) on the other. We booted into one OS, timed different tasks, then rebooted into the other OS and clocked those same tasks.
What's faster
The good news is that, of the 16 tests we ran, eight were indeed faster under Snow Leopard compared to Leopard. For example, an initial Time Machine backup to an external FireWire 800 hard drive was between 10 and 15 minutes faster in Snow Leopard. Snow Leopard was, on average, 32 percent faster with Time Machine backups across the three systems. Of course some of that performance benefit is due to Snow Leopard's smaller hard drive footprint - the iMac, for instance was backing up approximately 27GB worth of files under Snow Leopard, while Leopard's files and folders took up around 34GB of disk space.
Snow Leopard was also faster than Leopard during shutdown. On our iMac and Mac Pro, it took 7 seconds to shut down when running Leopard, but only 4 seconds when running Snow Leopard. For people using a desktop Mac, that difference may seem trivial. But laptop users who find themselves tapping their toes waiting for shut-down should take notice: Snow Leopard took half as much time as Leopard to turn off our MacBook Pro, 3 seconds versus 6 seconds.
Our Compressor test, which involves encoding a .mov file using Apple's H.264 for Video Podcasting presets, was 2 percent faster on our iMac and MacBook Pro and 4.5 percent faster on our Mac Pro when running Snow Leopard than when running Leopard. Zipping a 2GB folder in the Finder was 6.5 percent faster on the iMac, 8 percent faster on the MacBook Pro and 11 percent faster on the Mac Pro. Importing 150 photos from the hard drive into iPhoto, the iMac was nearly 8 percent faster under Snow Leopard, the MacBook Pro improved 11 percent, and the Mac Pro knocked a full 21 percent off the time it took compared to Leopard.