> If you want to examine a little more closely the "real root cause" you
> can do so by downloading "process explorer", run it, double click on
> ruby.exe, choose the "Threads" tab then double click on the thread
> number that seems the most active.  It will show you the method it's
> currently in (and chances are, the one it is bottlenecking on).

...as well as Mark and Bryce's other tools

http://technet.microsoft.com/en-us/sysinternals/dd535533.aspx
http://technet.microsoft.com/en-us/sysinternals/bb896645.aspx