The customer had a variety of desktop systems and we were replacing them all with identical Pentium III 1Ghz systems. We upgraded the server disk storage to RAID 0/1 at the same time. We started the desktop replacement with two systems side by side.
We did a number of (mainly subjective) performance evaluations. The first system went like a bat out of hell. Tasks which had taken minutes now completed in seconds.
The second system, however, was as slow as a wet weekend. The problem appeared to be network delivery. Yet both systems were identical.
We elimintated cabling problems, etc. I wrote a simple batch file which copied approx 100MB of data from the server to the desktop and wrote the start and end times to a log file. On the first system this took approximately half the time of the second system.
System one had a Canon LBP800 attached locally, which was accessed also by the second system. When the LBP800 drivers were loaded on the second system, it also loaded the status monitoring software. Removing this eliminated the problem completely.
This was first published in September 2001