[Twisted-Python] Twisted slow in Mac OS X fast on Windows

[Brian Granger]

Hi,

We use Twisted extensively in the IPython project for parallel and
distributed computing.  We have an extensive test suite that uses
trial to test our servers and clients.  Everything works
great...but...the test suite takes much longer to run on OS X than
windows.  Here is what I mean:

1.  2.53 Ghz Intel Core 2 Duo, Mac OS X 10.5.  Test suite takes 67 seconds

2.  *Same machine*, running Windows XP as VM in VMWare.  Test suite
takes 17 seconds.

I have verified that all the tests are being run on Windows.  This is
very surprising to me as I would expect, if anything, the Windows VM
to be a bit slower, not 3x faster.  This is the same hardware, the
same code, the only thing that I can think of that is different is the
reactor implementation.  I am using the default reactor on both
platforms.

Questions:

* Is the Windows reactor really that fast?
* Is the default (I think it is select) reactor on OS X really that slow?
* Why else would it be that slow on OS X?
* What can I do to speed this up?

Cheers,

Brian