Compression is inherently a disk- and CPU-intensive effort. The good news is that StuffIt Deluxe is optimized for multi-core speed and can take advantage of current dual- and quad-core processors to deliver fast performance when creating and opening archives.
From a competitive perspective, the two other popular compression programs are WinZip and PKZIP. As part of this review, I tested nine different file types for each program's capabilities. From a compression perspective, they all compressed to the same degree, with about a two to three percent differential, which is largely insignificant. Of the nine file types, PKZIP was best on four, WinZip on three, and StuffIt on two. But with differentials of two to three percent, this is insignificant from a performance perspective.
StuffIt Deluxe also has a new file format called SITX. This format is based on Aladdin's ATOM compression technology. StuffIt X makes archives with a .sitx file extension. According to the vendor documentation, when you create archives using the StuffIt X file format, you will see up to a 20 percent improvement over the existing StuffIt (.sit) format, and up to a 40 percent improvement over ZIP (.zip). By default, StuffIt Deluxe is configured to use the older StuffIt format (.sit) when creating archives. Testing the SITX format on the nine files has better compression in most cases. But for the plain text, it was actually larger.
After a question to technical support, the reason SITX is sometimes larger is that the ZIP and SITX formats have different methods for compressing different types of data. Each is better at certain things and not as good at others, though SITX should be better overall.
StuffIt 12 for the Mac has recompression technology that allows StuffIt to do a much better job of compressing some kinds of pre-compressed files (that is, PDF, MP3, and several image formats). These features will be added to StuffIt 12 for Windows, which should be out early in 2008.