I've modified one of the print statements into:

" PID ",b($$),". remote host: ",$ENV{REMOTE_HOST},"\n<br>",join(" ",ke
+ys %ENV),
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which now produces:

Fast CGI Rocks
Invocation number 0 PID 29716. remote host:
SCRIPT_NAME SERVER_NAME SERVER_ADMIN HTTP_ACCEPT_ENCODING HTTP_CONNECT
+ION REQUEST_METHOD HTTP_ACCEPT SCRIPT_URI SCRIPT_FILENAME SERVER_SOFT
+WARE HTTP_ACCEPT_CHARSET QUERY_STRING REMOTE_PORT HTTP_USER_AGENT SER
+VER_PORT SERVER_SIGNATURE HTTP_ACCEPT_LANGUAGE REMOTE_ADDR HTTP_KEEP_
+ALIVE SERVER_PROTOCOL HTTP_IF_NONE_MATCH PERL5LIB PATH REQUEST_URI GA
+TEWAY_INTERFACE HTTP_IF_MODIFIED_SINCE SERVER_ADDR SCRIPT_URL DOCUMEN
+T_ROOT HTTP_HOST UNIQUE_ID
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If I change my httpd.conf into

 SetHandler fastcgi-script
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I get a download popup-window