Mac OS X isn't the only operating system Apple engineers are working to improve. The company recently released OS 9.2.1, an update to the classic Mac OS aimed at improving application compatibility within OS X's Classic environment. But testing by Macworld Lab indicates that OS 9.2.1 doesn't noticeably boost performance -- at least not yet.
Apple originally introduced OS 9.2 as the default operating system on its new line of "Quicksilver" Power Mac G4 towers. But prior to the August 21 release of OS 9.2.1, Mac users who don't own the latest G4s couldn't purchase or download OS 9.2.
In contrast, OS 9.2.1 is available for download. Besides improved Classic application compatibility in OS X, Apple says the update adds additional hardware support for Macs capable of running the next-generation operating system.
However, Macworld Lab testing found little performance improvement in Classic applications running in OS 9.2.1. In tests performed in Microsoft Word and Excel, performance times in OS 9.1 and 9.2.1 were practically identical -- in fact, the 9.1 times were slightly better in scrolling, Excel calculations, and Word search and replace.
That's not to say OS 9.2.1 won't boost performance once OS X 10.1 ships. Performance boosts are rumored to be more significant in the updated version of OS X, slated for a September release, but there's no way of knowing for certain until Apple ships the software.
In addition to improving OS X Classic performance, the OS 9.2.1 update does have a few enhancements of its own that might be of interest to 9.X users. Most notably CarbonLib has been revved up to version 1.4, and QuickTime is up to version 5.0.2. Neither upgrade is exclusive to OS 9.2.1, however; OS 9.1 users can get them through software updates. Numerous other minor upgrades and bug fixes are present as well, but nothing dramatic has changed.
In short, this update is really targeted at OS X users. If you're running 9.1 with all of the updates installed, chances are 9.2.1 will not make much of a difference to you.