That page is way out of date. There's not really much IIS does other than hand off requests to a new or already warmed up php-cgi.exe (via the FastCGI bits). The performance stuff is really more down to the PHP maintainers (though Microsoft have contributed, and continue to do so).
The only pain point can be when there's a new release of PHP and you have customers who want to access MS SQL databases. This is done via Microsoft's own drivers [0] (Windows only). It's not been unknown for these driver releases to lag a bit behind PHP releases, but that said I see they're on the ball now with support for 5.6.
Other than that PHP runs just as quick and as reliably on Windows as it does on our Linux shared environments (I look after both).
The only pain point can be when there's a new release of PHP and you have customers who want to access MS SQL databases. This is done via Microsoft's own drivers [0] (Windows only). It's not been unknown for these driver releases to lag a bit behind PHP releases, but that said I see they're on the ball now with support for 5.6.
Other than that PHP runs just as quick and as reliably on Windows as it does on our Linux shared environments (I look after both).
[0]: https://www.microsoft.com/en-us/download/details.aspx?id=200...