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Compression Wars

by Ken Hancock -- -- khancock on AOL

With all the recent hubbub regarding the various file compressors, I thought it was well past time for a review and comparison of the leaders: StuffIt, Compactor (now Compact Pro), and DiskDoubler.

Before I begin, let's lay down the foundation used for the timing tests:

All tests were done on a Macintosh SE/30 with 8 MB memory, running 6.0.7 under Finder on a Wren IV drive. The only INIT running was Desktop Manager (no, I wasn't going to wait for my desktop to be rebuilt). Three different tests were performed on each application and each compression mode, each trying to reflect different real-world situations:

I tested six different applications: StuffIt 1.5.1, StuffIt Classic 1.6, StuffIt Deluxe 1.0, StuffIt Deluxe 2.0, Compactor 1.21, and DiskDoubler 3.1. In each case, the times were based on the time to compress an entire folder from the respective application in a one-step process. For DiskDoubler, this meant using its "Combine" feature since DiskDoubler is most commonly used to compress single files. Since DiskDoubler combines and then compresses, only one compression mode is used throughout all the files. For the DiskDoubler "Smallest" mode test, smaller files might be possible by first compressing the folder and then combining the folder. All the other applications compress on a file-by-file basis.

Please note that these tests do not take into account any interface issues or shortcuts that one might use. In each case, I only recorded the actual time spent by the Mac in compressing or decompressing the file. You should also be aware that there are more variables that were beyond the scope of these tests, such as still more different file types and how the programs worked with smaller files. Working on a single small database file, for instance, might produce somewhat different results. There is simply no way to test all the possibilities, sorry.

So, who won? Good question. As with everything, it depends on the game being played. I judged the applications on two criteria:

  1. Absolute compression: which program compressed the files the most.

  2. Best Efficiency: which program yielded the best compression/minute.

In the case of a tie, the application that compressed the fastest garnered the top spot. All compression percentages are carried out to two decimal places since different applications calculated/rounded the values differently. "Efficiency" was calculated by taking the "% saved" and dividing by the number of minutes it took to compress the folder. For those who wish to see the gory details, take a look at the enclosed Excel spreadsheet.

Since I tested four separate versions of StuffIt and a total of 12 different modes/versions altogether, I've summarized the results below, with the following condition:

All StuffIt Deluxe 1.0 trials have been removed as well as all timings with StuffIt Deluxe/Classic "Better" mode. In almost all of the trial modes, "Best Guess" provided identical compression to "Better" mode, but at a faster speed. (One questions why the "Better" mode is even included.)

The results (a note for the less mathematically inclined - the larger numbers are better):

Compression Rankings

  Best Compression - Binaries        % saved    %/min efficiency
  StuffIt Deluxe 2.0 "Best Guess"    42.3             7.11
  Compactor                          41.94%          13.90
  StuffIt Classic 1.6 "Best Guess"   41.94%           5.67
  DiskDoubler 3.1 "Method B"         35.34%          11.91
  Best Compression - Graphics        % saved    %/min efficiency
  Compactor                          55.66%          11.80
  StuffIt Deluxe 2.0 "Best Guess"    55.10%           8.59
  StuffIt Classic 1.6 "Best Guess"   54.33%           7.12
  DiskDoubler 3.1 "Method B"         51.09%          19.52
  Best Compression - Text            % saved    %/min efficiency
  Compactor                          53.98%          87.54
  StuffIt Deluxe 2.0 "Best Guess"    52.59%          24.85
  StuffIt Classic 1.6 "Best Guess"   52.15%          27.94
  DiskDoubler 3.1 "Method A"         51.41%         140.21

Efficiency Rankings

  Best Efficiency - Binaries     %/min efficiency   % saved
  DiskDoubler 3.1 "Method A"         18.21           25.19%
  StuffIt Deluxe 2.0 "Faster"        14.62           13.89%
  Compactor                          13.90           41.94%
  DiskDoubler 3.1 "Method B"         11.91           35.34%
  Best Efficiency - Graphics     %/min efficiency   % saved
  DiskDoubler 3.1 "Method A"         39.15           47.63%
  StuffIt Deluxe 2.0 "Faster"        34.95           33.20%
  StuffIt Classic 1.6 "Fast"         28.34           49.13%
  StuffIt 1.5.1 "Try both"           25.51           48.47%
  Best Efficiency - Text         %/min efficiency   % saved
  DiskDoubler 3.1 "Method A"        140.21           51.41%
  Compactor                          87.54           53.98%
  DiskDoubler 3.1 "Method B"         83.22           48.54%
  DiskDoubler 3.1 "Smallest"         71.74           51.41%

Expansion Ratings

At least a few people out there want to decompress files for some strange reason and might be interested in how fast the various compression programs do this. Myself, I always go fix a snack, watch some Star Trek, read a book, or carry on intellectual conversations while my Mac decompresses files. I guarantee that me method will give you the best results (i.e. you'll enjoy yourself instead of sitting around watching progress bars). But, since I've so often been reminded that I'm probably not a good indication of the real world, here we go...

I did two decompression tests for each of five programs: Compact Pro 1.30, DiskDoubler 3.1, StuffIt 1.5.1, StuffIt Classic 1.6, and StuffIt Deluxe 2.0. All tests, as before, were performed on a Mac SE/30, System 6.0.7 running under Finder, and using the Desktop Manager. The first test was to decompress a StuffIt 1.5.1 archive containing all the previously compressed files: Binaries, Graphics, and Text Files. The second test was to decompress one file containing the same files in the application's native format. Compact Pro has only one format (simple, eh?). For DiskDoubler, this was a "combined" file compressed with Method A. For StuffIt 1.5.1, this was a file compressed with "Try both." For StuffIt Classic and Deluxe, this was a file compressed with "Best Guess." I decided to use these formats because I thought they would be the most commonly used in each case (I could be wrong) and since decompression times will vary widely depending on %-saved, original data type, etc. (So use these numbers only as a rough guideline!)

Two figures are given for each application. For the first test, we have total time to decompress the 2,527,112 byte file (the faster, the better) and a speed relative to StuffIt 1.5.1 (the larger the number, the better). For the second test, we have total time to decompress the file and a kilobytes/minute decompression speed (again, the larger the better).

Time to decompress a StuffIt 1.5.1 archive:

                     Time       Normalized
  Compact Pro        2:41         1.95
  DiskDoubler        3:51         1.36
  StuffIt Classic    5:07         1.02
  StuffIt 1.5.1      5:14         1.00
  StuffIt Deluxe     5:24         0.97

Time to decompress a native format file:

                     Time        K/min
  Compact Pro        3:26         732
  DiskDoubler        2:23         635
  StuffIt 1.5.1      5:14         472
  StuffIt Classic    7:11         390
  StuffIt Deluxe     7:33         365

Question: "So, which one should I use?"

Answer: "It depends on what you want. Read on."


Compactor, a relatively recent introduction into the compression world from Bill Goodman, takes the simple approach: easy, fast, and compact. In all of the trials, Compactor files were never more than 1% larger than StuffIt Deluxe's "Better"/"Best Guess" modes, but anywhere from 25% to 400% faster. Compactor is currently my choice for daily BBS and Usenet uploads and downloads. Compactor also featured the absolute fastest decompression times for both StuffIt 1.5.1 files and for its own files. In addition, Compactor creates the smallest self-extracting applications (about 13K overhead), which is handy if the recipient doesn't have the same program you use. It also works the way an application should under MultiFinder and allows the foreground application to work quickly while still managing to get its own work done. (Nice job, Bill!) Now only if it had Finder-level compression...

Of course, if you are up on the absolute latest and greatest, you know that Bill Goodman just released a new version, Compact Pro 1.3 (he had to change the name because of a name conflict with another product). The times and archive sizes were ever so slightly longer and larger, most likely due to the removal of the 300 files per archive limit that Compactor had. I didn't change either the results in the article or the spreadsheet because of the minimal differences between Compactor and Compact Pro file formats. Most Compact Pro archives can be extracted by Compactor unless they take advantage of one of the new features, such as the removal of that 300 files per archive limit I just mentioned. Compact Pro boasts plenty of other features that should help solidify its position as the shareware compression program of choice. If you hold down the option key when double-clicking on an archive, Compact Pro automatically extracts all the contents. Similarly, double-clicking on filenames in the archive catalog window extracts the files, as it should. For those on the Internet, Compact Pro now supports Binhex 4 encoding and decoding, though it can't decode binhexed files that have text before the start of the binhex codes. Curious, and Bill is probably working on that right now. Overall, though, Compact Pro is well worth the $25 shareware fee.

Bill Goodman
109 Davis Ave.
Brookline, MA 02146
71101,204 on CompuServe


I've been a big fan of StuffIt ever since Raymond Lau released it way back when. Before that, PackIt was the standard, and it didn't take long before everyone noticed that StuffIt was faster and better. Since then, StuffIt development and marketing has been taken over by Aladdin Systems. The results: StuffIt Classic, the new shareware version, and StuffIt Deluxe, the commercial version. StuffIt Classic improves upon StuffIt 1.5.1 by offering better compression modes, the ability to navigate through folders, support for externals, and virus checking. StuffIt Deluxe goes beyond StuffIt Classic by offering extensive scripting, more compression methods, compression "optimizers," compression "externals," and my favorite feature, "Magic Menu." Magic Menu not only allows Finder-level compression, but also includes hooks for popular mail programs so you can stuff & send files. StuffIt Deluxe is my compressor of choice at work for the Magic Menu feature alone. On the downside, StuffIt Deluxe is beginning to suffer from feature-itis. It seems to me that five different compression methods is more than needed, especially since "Best Guess" and "Better" yield almost identical compression factors.

While StuffIt certainly wins the features wars, it isn't always the most efficient format, and one place where Compact Pro wins is in the size of the self-extracting archives. Depending on what mode you choose, StuffIt adds between 19K and 23K to the compressed file to make it self-extracting. In contrast, Compact Pro only adds about 13K, which can be a big difference when you send files at slow modem speeds. StuffIt Deluxe and StuffIt Classic also brought up the rear in terms of decompression speed, which is something of a strike against them.

Aladdin Systems -- 408-685-9175
Deer Park Center, Suite 23A-171
Aptos, CA 95003
Aladdin on America Online


DiskDoubler was the biggest surprise for me, probably because I was least familiar with it. When I ran the "Text" test on it, all I could say was "Wow." No wonder Apple decided that a site-license for it would be a good thing. DiskDoubler fills a different niche than StuffIt and Compactor. DiskDoubler provides near-transparent file compression in normal use. Compress a document or application from the "DD" menu in the Finder. The document icon is then replaced by a copy with a little "DD" in the corner (only if DiskDoubler has been configured by Salient for that particular application). Weeks later when you need the document, double-click, and it (and its associated application, if that is compressed as well) is decompressed and opened. Quit from the application or close the document and DiskDoubler recompresses the document, and if appropriate, the application. Slick! Decompression wasn't quite as impressive as compression, but DiskDoubler took second place by quite a large margin nonetheless. The NuBus DoubleUp board (SE and SE/30 versions to follow) from Sigma Designs, currently in beta test, will make DiskDoubler up to ten times faster and may shrink the compressed files more as well.

DiskDoubler has no provision for self-extracting archives because it isn't trying to compete in the online compression battle between StuffIt and Compact Pro. Instead, DiskDoubler includes a freely distributable application and INIT, both of which can only expand compressed files. They aren't all that small, at 82K for the INIT and 96K for the application, but you only have to send them to your intended recipient once. If you regularly send self-extracting archives to the same person, sending DiskDoubler's free utilities is probably more efficient.

I have only two gripes about DiskDoubler. First, the progress window is a little obtrusive. I'd prefer a small, relocatable windoid. Luckily Salient has said they may include options for either a smaller window or no window in future versions to make DiskDoubler even more transparent. Salient also mentioned that although the progress window is modal, it does allow background tasks ample time. Second, there aren't enough icons included - the perfect solution would be an application that allows you to add icons from an application and put the "DD" in the corner - better yet, do it on the fly! (Thanks to Tom Zeller for loaning me a copy so I could review it - the only problem is I was so impressed that now I'm going to have to go out and buy yet a third compression program!)

Salient -- 415-321-5375 -- 800-326-0092
124 University Ave. Suite 103
Palo Alto, CA 94301
Salient on America Online and AppleLink
76516,1574 on CompuServe

Compression Conclusions

The common denominator remains the old StuffIt 1.5.1 format, since all of the compression programs can expand 1.5.1 files (this is why we included a StuffIt 1.5.1 file in the decompression tests). Not surprisingly, StuffIt Classic and StuffIt Deluxe can also create 1.5.1 archives, unlike the others. However, most of the online services, including the Internet file servers, have adopted a policy of allowing any format if a free decompressor is available. America Online is the major holdout, since it prefers uploads in StuffIt 1.5.1 format and only allows other formats if the files are self-extracting archives.

Yet another program will try its hand at the competition soon, when Alysis Software releases SuperDisk!, which is designed to compete with DiskDoubler and provide transparent compression and expansion of files. However, SuperDisk! will also go after the other programs by creating smaller archives in less time and by including the ability to create self-extracting archives. It should ship in a month or so. If that's not enough for you, a shareware program recently appeared on the scene to compete with DiskDoubler. AutoSqueeze from Dawson Dean transparently compresses and expands files or folders (and the files in them) whose name ends with the word "compressed." It's $20 shareware and works quite well, though in our informal tests it isn't as fast as DiskDoubler nor does it compress the files as much. A friend was recently bemoaning the number of choices in the compression field. "It all used to be so easy," he complained. "Everyone loved StuffIt and thought Ray Lau was a god. Now we've got a ton of formats to deal with and trade-offs wherever you look." There is something to be said for simplicity, but we're unlikely to ever see it again in the compression field.

The bottom line? It's a toss-up. I'll be using all three - StuffIt Deluxe for the Magic Menus and mail hooks (not to mention JPEG compression for Photoshop documents!), Compact Pro for my uploading and downloading, and DiskDoubler to compress all the infrequently-used files on my hard disk (definitely cheaper than buying another hard disk). And by the way, don't try these tests at home - compressing files for eight hours with a stopwatch is not in my "Top 10 Things To Do" list.

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