CGI vs FastCGI

Hi,

I have to develop an C++ application that will be used on a web server 
and to choose the most performant interface between CGI and FastCGI. 
Therefore I've done a trivial performance test with an simple "hello 
world" application to compare both interfaces.

I've made the test with this configuration :

    * Intel Core 2 Duo E8400 @ 3.00Ghz
    * 256Mb RAM
    * Linux version 2.6.26-2-686 (Debian 2.6.26-15)
    * lighttpd-1.4.19 (ssl)
    * ApacheBench v2.3

The Lighttpd config is the default config and I've loaded mod_cgi and 
mod_fastcgi. Only one process is running for FastCGI.

The results of the test (running on localhost) with 1000 requests and a 
concurrency of 10 are :

    * 5000 req/s with FastCGI module
    * 100 req/s with CGI module.

Can I trust these results (big difference)? Has someone already done a 
performance test between these two interfaces? And how were the results?

Thanks for your answers.