2. Cut out the non-native code

When Apple made the transition from PowerPC to Intel processors in early 2006, it needed to provide solutions for two major problems. First, since Intel processors couldn't natively run code designed for PowerPC processors, Apple introduced Rosetta, a technology that allows an Intel Mac to emulate a PowerPC processor on the fly as needed to run PowerPC code. Rosetta makes all Intel Macs able to run software that has not been updated to run natively on an Intel processor.

As with any type of emulation, however, this is a drain on processing power and performance. So one of the biggest performance advances you can make on an Intel Mac is to get rid applications that are PowerPC native. Unless you're working with specific older applications, you should be able to manage this by updating your installed software, as most developers now offer Intel-native or universal binary applications. (The last major holdout was Microsoft Office, which now supports Intel processors with Office 2008.) You should also ensure any non-application executables like third-party preferences panes are also updated.

The second challenge Apple faced in moving to Intel CPUs was providing a mechanism, known as a universal binary, that would allow developers to offer a single application that would run natively on both Intel and PowerPC Macs. Universal binaries achieve this by including both the Intel and PowerPC native code. While effective for making application distribution easier for developers and users, universal binaries double the size of the code contained in an application.

The utilities mentioned in the previous tip can all be used to remove this excess code from your installed applications, slimming down your system. Don't expect all your applications to be immediately cut in half, however, as most applications include files beyond just code (files that define dialogs, windows and menu items, for example).

Note: If you have a mix of Intel and PowerPC Macs and you need to copy applications between them, you may want to skip this space-saving tip, since it will effectively create PowerPC-only and Intel-only versions of your applications.

3. Trim down iLife media libraries

Perhaps nothing takes up as much space on a Mac's hard drive as media collections. Apple's iLife suite allows you to maintain libraries for iTunes, iPhoto and iMovie that store your media; make them easy to search or browse; and make them accessible throughout Leopard and other apps. These libraries can take up a lot of space. For many people, however, simply culling material isn't a valid option, as that means giving up music, photos and video that you want to keep. Here are a couple of other options to consider.

First, if you have an external hard drive, consider relocating your media library to it. This will keep your media but free up space on your internal hard drive. This can be done with each library, but is probably most effective with video. While you may want your music and/or photos accessible at a moment's notice, that's probably not the case with your video library.

If you're using a portable Mac, consider building separate libraries on both your internal and external drive. This gives you access to your entire library while your machine is plugged into the external drive at home or work, and you can also have a small subset of music or other media—such as movies to watch on a plane—with you at all times. Tools like Syncopation ($25; free trial) and iPhoto Library Manager (free; advanced version $20) can help you manage this dual-library existence.

Another option that has both organizational and disk-saving options for iTunes and iPhoto is to search for duplicates in your library. With thousands of songs and photos, having duplicate tracks or photos is a very real possibility.

De-duping in iTunes
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Both iTunes and iPhoto provide basic duplicate detection features, but those features may not always turn up all your duplicates. iTunify ($15; free trial) and iSweep ($15; free trial) provide advanced duplicate detection for iTunes, and Duplicate Annihilator ($8; free trial) provides in-depth detection for iPhoto.