Hi Tontang,
I don't really understand the first part of your question. You seem to be implying that CGI is (memory intensive / has memory leaks / is slow / ...?). However CGI stands for
Common Gateway Interface - it describes an interface, not an implementation. How that is implemented, and the language that the clients are written is, is not defined (if they were defined, the interface itself may not be required). So it is quite possible to have a CGI compliant application and server which scales well (CPU / memory / TPS / ...). And going to Java (or Ruby, or any other language) does not automatically mean that we are going to get any improvement in scaling.
Which is not saying that CGI is better than Java - just that the fact that it is CGI does not automatically mean that it is bad.
Moving forward though - your question as to whether there is anything that CGI offers that couldn't be done with some other technology, or if there is anything we particularly like about CGI: No on both counts.
However you are sort of getting to a very frequently asked question: why are we using CGI (or why are we not using Java). So you might want to take a look at
this.
Regards, Andrew