>
> Are there any noticable differences in performance between firebird on
> the windows and linux out of the box?

Out of the box, you are better advised to run WinOS with Forced Writes ON.
This will lower performance a tiny tad.
Also it's argued theory that since Linux is not running a GUI then more CPU
cycles are available to server processes.
That said - I have servers on both environments and I'd have to do some
pretty long running test to see the difference and when you ignore thory and
put a reall application against it - conclusion would be "it depends"
I'd recommend going with your gut and your personal preference.

> Also does it make much difference when making the decision between super
> server and classic archictectures on linux with nptl or linux threads?
>

I think you need a lot more RAM to run Classic effectively. Classic has
never been touted as the final thing for Windows, it's more a Linux build as
far as I know.
But classic I think is supposed to cater for greater concurrent users that
superserver.
I'm sure there are other ready to comment further on this
Alan