kpbg4: My PowerBook CPU is running slow

My PowerBook CPU is running slow since installing a Mac OS X update.
Problem:
When running either of the Terminal (Applications > Utilities > Terminal) commands "sysctl hw.cpufrequency" or "sysctl hw help" my CPU speed is reported as lower than it's actual value.
When running certain applications such as Xbench 1.1.2, Onyx, Halo or VirtualPC, my CPU speed is reported lower than it's actual value.

Affected Machines:
All PowerBooks and iBooks can be affected by this, examples include;
- 12" Aluminum PowerBook 867MHz being reported as 533MHz.
- 15" Aluminum PowerBook 1GHz being reported as 667MHz.
- 15" Titanium 800MHz PowerBook being reported as 667MHz.

Discussion:
With the 10.2.8 Mac OS X update Apple implemented a new power management configuration file which included activating the speed-stepping feature of the G4 processor more aggressively to extend battery life. Many applications query this file for the CPU speed rather than querying the CPU itself. This can cause certain applications to report the CPU speed as lower than it actually is as they return the lower-speed setting. In other cases (such as XBench), the application will query the CPU in it's "stepped-down" state, and therefore return an incorrect speed.

Using the 867MHz 12" PowerBook as an example, the above Terminal commands will report the CPU speed as 533333332 when you would expect it to report as 866666664.

Solution:
This is purely a cosmetic issue. Your PowerBook is not running slow. You can perform a few tests to verify your machine is running correctly by installing a version of OS X prior to 10.2.8 and trying the following;
- Play an intensive 3D game and record the frame-rates.
- Run XBench and save the output.

Now update to 10.2.8 or above and repeat the tests. You will see almost no variance in the scores*, showing your CPU is running at full speed and the issue is cosmetic. You may also wish to compare your XBench scores to the benchmarks on their web-site.
*Note: If updating from 10.2 to 10.3 you will likely see a noticeable positive jump in your results due to the ongoing optimisations made to Mac OS X, however the CPU scores will be very comparable.

Many applications have been updated to reflect this change, the XBench 1.1.3 update "fixed CPU and cache speed reporting on iBooks/PowerBooks under 10.2.8" so it pays to keep your software up-to-date. Run Software Update (System Preferences > Software Update > Check Now) regularly and use the in-built automatic updating feature of many mainstream applications or VersionTracker to ensure you stay on-top of updates.

Matt
17/04/04 - Original document.
26/11/04 - Updated links, formatting and clarified problem description.