Tuning Mac OS X Performance

This FAQ provides recommendations for optimizing Mac® OS X performance. Additionally, it provides advice and links to advice for troubleshooting certain Mac OS X performance problems. Comprehensive advice on this topic can be found in the "Performance" chapter of our book Troubleshooting Mac OS X.

Optimizing Mac OS X performance

RAM, RAM, and more RAM

Mac OS X loves RAM. Short of buying a new Mac or a processor upgrade, adding RAM is the best way to improve Mac OS X performance. Install the maximum amount of RAM that your Mac will accept and your budget will allow.

Maintain ample free space on your startup disk

Mac OS X makes extensive use of Virtual Memory (VM), which requires free disk space on your startup disk, aka your boot volume. If you startup disk is nearly full, your Mac's performance will degrade considerably.

Turn off the eye candy

While I imagine everyone is impressed the first time they see a window minimized to the Dock with the Genie effect, this entertainment has a performance cost. You can gain some speed by avoiding the eye candy.

  • Make the Dock less entertaining
    1. Open System Preferences > Dock.
    2. Select Scale Effect in the Minimize Using field.
    3. Deselect the Animate Opening Applications option.
  • Disable window effects
  • Tools such as Cocktail and TinkerTool provide options to disable effects, such as zoom and rectangle, that appear when windows and files are opened and closed. The actual settings these utilities change are already available in Mac OS X but are "hidden" as there is currently no provision for changing them in System Preferences.
  • Avoid using an animated desktop background
  • While entertaining, an animated desktop background steals cycles from other processes on your Mac. It is better to have a static picture as your desktop background if performance is important.
  • Skip the iTunes® Visuals
  • Running iTunes Visuals in the background consumes valuable processor cycles, especially when you are performing other computing tasks. It is not so much displaying the visuals as the computational effort needed to synchronize them with the music in real time that makes them so processor-intensive.
  • Close nonessential Dashboard Widgets
  • While Dashboard widgets do not use the CPU unless Dashboard is open, they consume both Real and Virtual Memory (VM) at all times after you open Dashboard. You can see this by reviewing the data for each widget in Activity Monitor. You can reclaim these resources by closing nonessential widgets. To close a widget:
    • Open Dashboard.
    • Press and hold the Option key.
    • Move the mouse pointer over a widget you wish to close. The widget's Close button (X) appears in the upper-left corner of the widget.
    • Click the widget's Close button.
    • Repeat steps 3-4 for other widgets you wish to close.

Repair Permissions after installing new software

Run the Disk Utility > Repair Disk Permissions against your Mac OS X startup disk after any software installation. While I expect the need to do this will diminish in time, one must still be wary of installers that do not reset permissions correctly after an installation.

Disable the automatic protection features of utilities

Utilities that constantly monitor your system for performance, automated data recovery, or viruses also use processor cycles. There is an obvious trade-off between these functions and Mac OS X performance. If performance is critical, disable the automatic protection features of such utilities, usually via their Preferences.

Disable or remove unnecessary fonts

Loading hundreds or thousands of fonts by default can significantly degrade Mac OS X performance. This is especially true if you use Font Book to install fonts and have not adjusted its preferences: by default, Font Book automatically enables newly-installed fonts.

If you have hundreds or more fonts to manage, consider using Font Book or a third-party font-management application to create, enable, or disable font collections when required.

Perform regular maintenance

While Mac OS X is relatively maintenance-free, by regularly performing the tasks outline in our "Maintaining Mac OS X" FAQ, you will help assure the best performance from your system. At a minimum, run the Mac OS X maintenance scripts regularly.

Check your processor performance setting

Some Macintosh computers can decrease the processors speed to conserve energy. To adjust the processor speed, click Options in System Preferences > Energy Saver and make the appropriate adjustments in the Processor Performance menu. Note that:

  • If Options is unavailable in Energy Saver preferences, your Mac does not have this capability.
  • If you are using a laptop on battery power, increasing the processor performance will shorten the amount of time you can use the computer at the battery's current state of charge.

Troubleshooting performance problems

Finding processes or applications impacting performance

To determine if a specific process or application is impacting performance:
  1. Launch Activity Monitor (Tiger™, Panther®) or Process Viewer (Jaguar) by double-clicking its icon in the Macintosh HD > Applications > Utilities folder.
  2. In the Show pop-up menu in the toolbar of Activity Monitor or Process Viewer, assure All Processes is selected.
  3. Sort the list of processes by %CPU in descending order:
    • In Activity Monitor, click the %CPU column heading until the data in that column is sorted in descending order.
    • In Process Viewer, click the %CPU column heading, then click the arrowhead at the right side of the column headings until the %CPU column is sorted in descending order.

The process or application using the greatest % CPU is now at the top of the list.

To terminate a process
  1. Select the process you want to terminate in the list or processes.
  2. Press the Command-Option-Q keyboard combination or use one of these other application-specific methods to terminate the selected process:
    • Tiger: Select View > Quit Process or select the Quit Process icon in the toolbar.
    • Panther: Select Process > Quit or select the Quit Process icon in the toolbar.
    • Jaguar: Select Process Viewer > Processes > Quit Process.

Note that both applications you have launched and background processes, which are in themselves applications, are all regarded as processes. Process names you recognize are probably applications you have launched. Process names you do not recognize are likely background processes.

Warning: Quitting a background process can have unexpected results, so you should consider this before quitting a process you do not recognize. An excellent list of Mac OS X background processes is Westwind Computing's "Mac OS X: What Are All Those Processes?" page.

However, the worst outcome from quitting a background process is that you will have to restart your Mac. Therefore, if your system is frozen or hung, try terminating the process using the most % CPU as described above.

If you are unsure how a specific application or process was launched, see if it is a Startup or Login Item.

Resolving common performance problems

SystemUIServer: high CPU usage and menu extras

If Activity Monitor (Tiger, Panther) or Process Viewer (Jaguar) indicates that the process SystemUIServer is consuming an inordinate amount of CPU, the problem is very likely related to a third-party menu extras. Menu extras are the icons on the right side of the Apple menu bar other than the Spotlight icon (Tiger).

Third-party menu extras that use an active Internet connection can result in very high CPU usage if the network connection becomes busy or blocked. The chances of this increase if you are simultaneously using streaming media and a menu extra that requires an Internet connection.

Quitting your third-party Menu Extras should resolve the problem. For additional information, see our "Troubleshooting Startup and Login Items" FAQ.

Other common performance problems

Troubleshooting information for a variety of performance problems related to specific Mac OS X components can be found in the following sections and chapters of Troubleshooting Mac OS X:

Did you find this FAQ helpful? You will find a wealth of additional advice for preventing or resolving Mac OS X problems in Dr. Smoke's book, Troubleshooting Mac® OS X.
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