I am creating a webapp which consists of a very few main scripts. And I wonder - is better AND faster to use some specific rules (from about 10 to 20)
Or is it better to use some general rule e.g. http://example.com/go/my/boy would come to go.php?my=boy ?
This question is (more or less) about PERFORMANCE :)
EDIT: I dont have the resources to make a performance test by myself.
You are splitting hairs. As far as Apache performance when it comes to rewrites, alias & redirects there is a very slight performance hit when you add more rules. But it is negligible to imperceptible in practical use. And FWIW, this is a fairly common rookie perception when it comes to Apache performance.
Meaning, if you are worried about application performance, optimizing your application itself—and not the Apache web server—will give you the best & most measurable performance improvements.