Question about long-running web scripts

[Gilles]

Hello

I'd like to check something about running Python web applications.

Generally speaking, the reason scripts run faster when called through
FastCGI or the mod_* modules, is because the interpreter is already up
and running.
But when running PHP scripts, this does nothing about fetching the
file from disk, recompiling, rerunning it, and usually reconnecting to
the database.

OTOH, Python web scripts can be written as long-running scripts: In
this case, what is the added-value of using FastCGI? Why can't the web
server simply call the Python script directly, just like CGI?

Thank you.