Apple has already announced the successor to Leopard, called Snow Leopard, during the WWDC not too long ago. They explained that Snow Leopard would not focus on user-visible features, but instead would deliver performance improvements and resource footprint reductions. One of the measures Apple has taken is the size reduction of application bundles, which has resulted in dramatic weight loss for a lot of applications. AppleInsider has found out what exactly Apple has been doing
to lose that much weight.
The weight loss in Snow Leopard's bundles is astonishing in many cases; for instance, Mail.app went from 287MB in Leopard, to just 91MB in Snow Leopard. Another good one is Image Capture, which went from a very fat 15MB to just 1MB. How exactly did Apple achieve such a weight loss?
One measure is the fact that Apple has removed the various localisation files from each application, relying on a centralised container instead from which application can draw the things they need. Another measure is the compression of Interface Builder's NIB files; NIB files also contain the graphical resources. In addition, Apple lost weight by deleting the designable.nib files from bundles - they are the xml files used during development, and they shouldn't be in the final builds, but due to an error by Apple, they were included anyway in Leopard's bundles. Compressing the NIB, xml, and html files in Leopard's mail already reduces Mail.app from 289 to 96.6MB.
While Apple may likely be expanding the use of background file compression to save space in Snow Leopard, today's Mac OS X Leopard is unnecessarily overweight due to an error Apple made when packaging the system, according to a developer who asked to remain anonymous. Leopard apps all contain superfluous designable.nib files that should have been removed in the Golden Master. "Mail alone has around 1400 of these files, taking up almost 200 MB of disk space," he noted.
The last important measure is resolution independence. Resolution independence relies on vector graphics, which take up less space than ordinary graphics resource files. Which brings us the final point where size reduction could benefit from, according to many - the ditching of PowerPC code from universal binaries. According to reports, this hasn't happened yet, and it wouldn't make much of a difference anyway.
As for the removal of PowerPC code, developers note that Snow Leopard's applications are still currently being delivered as Universal Binaries anyway, and that removal of that extra code has a very limited impact on file size when compared to the results of compressing large XML and graphics files related to interface localization and the complete removal of any unnecessary development NIB files.
You can achieve similar results on Leopard already with tools such as MonoLingual and Northern Softworks Leopard Cache Cleaner. Deleting the designable.nib files helps too.