Oh yeah, I forgot about this one! It's actually pretty much the first thing I ever put on this site--I mean even before I had the actual comic site and top menu and stuff.
That animation should play back in exactly one minute. No computer and browser combination that I know of will actually play it back in precisely one minute, but in Internet Explorer, you can actually watch the clock get slower with each passing frame (1/10th of a second), until it is running at something like half speed, and taking up most of your CPU usage; then once it loops after 60 "seconds," it's back up to full speed, but immediately begins slowing down again...
The full demonstration is here
, where you can see it compared against the same animation in .swf format; they'll both slow down in IE later in the "minute" because the .gif will be draining your CPU, but you should be able to see the .swf clock running significantly ahead of the .gif clock.