[Tim Peters]
The Intel compiler tries to exploit special short-vector hardware that's of great use in number-crunching apps that spend most of their time in tight, regular, numeric inner loops, but sits idle otherwise. There's very little of that in Python or Zope.
[Morten W. Petersen]
Would the difference be negligible?
It's impossible to say without trying it. The referenced article was specifically about number-crunching benchmarks.
What compilers are currently used for Windows/Linux?
If you build Zope yourself, whichever compiler you used <wink>. The C library is also important, and so is the OS. The PythonLabs Windows Python is built with MSVC 6.
Are 'better' compilers available?
I'm afraid there aren't easy answers here. "Try it and time it." Fiddling compiler optimization switches to favor your specific hardware can also be a big help.