Here's the trace: http://pastie.org/668078
OS: Mac OS X 10.6.1
Ruby: ruby 1.9.1p129 (2009-05-12 revision 23412) [i386-darwin9.7.0]
I don't have snowleopard yet but I can test on 1.9 at least.
Can't install on 1.9.1 p376, on windows, mac osx, or linux.
Windows - http://pastie.org/745125
Linux - http://pastie.org/745129
Mac - http://pastie.org/745131
Oh, now that I think about it, it's going to take a lot of work to get date-performance running under 1.9. They've changed a ton of stuff with Date. I'm not sure when/if I'll get around to it.
This may be a 1.8.x only library unless someone wants to take a crack at porting to 1.9.