I really don't care about performance on IIS or Win32, but if you do you should:
* Try a dummy PHP script as well as MediaWiki itself * Use MediaWiki's built-in profiling to see if the slowdown is isolated * Compare with/without eAccelerator or Turck MMCache (note that Zend Optimizer is *not* comparable to these; it's a different product which is primary a loader for precompiled/obfuscated scripts created with another Zend product and secondarily does some peephole optimizations in the compiled code, which apparently make very little performance difference in practice) * Try disabling $wgEnableSorbs, sometimes reported to help with very long delays on intranets with broken DNS
-- brion vibber (brion @ pobox.com)