ISPConfig is not starting more then 2 or 3 connections. I guess what you see are the connections started by postfix. You can not reduce that as postfix has to start a connection for a incoming email to determine the correct destination for the email. But thats not a problem, mysql is able to handle hundreds of connections well.
thank you very much till ... i used the mysql standard configuration from ubuntu - so i really had a problem ... perhaps it would be a good idea to create an db-user ispcpostfix during install, so that nobody can blame ispconfig when looking at mysql processes ;-) cheers
You can optimize your MySQL configuration with MySQLTuner: http://www.howtoforge.com/tuning-mysql-performance-with-mysqltuner