Here is a quick and experimental add-on to offer FastCGI speed to any Perl script (without requiring it to be modified):
* Download http://www.aprelium.com/data/PerlFCGI.zip and uncompress it inside your Abyss Web Server installation directory inside a subdirectory named PerlFCGI
* Follow all setup instructions in http://www.aprelium.com/abyssws/perl.html but apply these two differences:
- Set Interface to "FastCGI (Local - Pipes)" or "FastCGI (Local - Pipes)" instead of "CGI/ISAPI"
- After locating the perl executable, set the "Arguments" field to:

-I"C:\\Program Files\\Abyss Web Server\\PerlFCGI" "C:\\Program Files\\Abyss Web Server\\PerlFCGI\\run.pl"

Note that you should substitute in the example above C:\\Program Files\\Abyss Web Server\\ with your actual path of Abyss Web Server installation directory.
Note also that you'll have to use two back slashes \\ instead of single backslash \ in path names (this is required in the arguments line).
If you use forward slashes /, there is no need to double them in the arguments line.
With such a setup, .pl and .cgi scripts will use FastCGI interface instead of CGI. There is no need to change anything in their source code.
Here is simple test.pl for testing purposes:

use CGI qw/:standard/;

print header,
    start_html('A Simple Example'),
    h1('A Simple Example'),
    start_form,
    "What's your name? ",textfield('name'),p,
    "What's the combination?", p,
    checkbox_group(-name=>'words',
                   -values=>['eenie','meenie','minie','moe'],
                   -defaults=>['eenie','minie']), p,
    "What's your favorite color? ",
    popup_menu(-name=>'color',
               -values=>['red','green','blue','chartreuse']),p,
    submit,
    end_form,
    hr;

if (param()) {
   print "Your name is",em(param('name')),p,
         "The keywords are: ",em(join(", ",param('words'))),p,
         "Your favorite color is ",em(param('color')),
         hr;
}

We'll be waiting for your feedback on this add-on (which is a quick hack and not fully tested).