The browser does not wait for such long and it throws an "Internal Server error".

Nope, the SERVER generates that message, either because it KILLED your CGI for being far too slow, or because your CGI has crashed. Look at the error log to see what went wrong. If you don't have access to the error log, search for a better provider. Inserting ...

... right after the first line may help you to debug your problem while you can't access the error log. Remove that line after you finished debugging, so you don't give additional information to malicious users.

Alexander