4) Note: times for Unix and VMS are 'user' time (the part of the real time which OS gave to gzip); the rest is 'real' time. (for gzip 1.2.4 with Think C command line interface and for DOS gzip would be the same as user time, for the rest, we don't know how much of the time our application was running and how much was used for background tasks)
5) MacGzip:
MacGzip is not the same program as 'gzip 1.2.4', since it draws windows, progress bars, does some translations while reading/writing to disk, etc etc, so it always will be slower. This is the price of a GUI…
About real and user time, in a real multitasking system (Unix) the performance is better, since if no other process is running, the system won't interrupt ours (well, not too often); but in MacGzip, we give the control to OS every few instructions; regardless if it needs it or not.
Before you ask, no, I don't know why decompression is so slow; maybe is because of the checks I have to make when writting in order to see if is macbinary, ascii, etc…
6) Some of the machines have more than one CPU; but gzip is not a parallel program, so it does not makes any difference.