I want to host websites with a xml-based CMS (like GetSimple) in which the data is stored in xml files rather than mysql database. Thus, I do not need mysql database. On the other hand, I wish to have a simple control panel (only for domain management) to simply add domains instead of dealing with SSH commands.
Is there a simple control panel which does not use mysql? Since my websites do not need mysql, I hope not to install it to save memory and CPU usage.
You don't need to look for a "special" control panel, you can simply disable the MySQL service. This is easy to do in cPanel and DirectAdmin for instance. And why stop there? Disable the mail servers and spam filtering if you host your email externally, and the DNS servers if you can use alternative nameservers, the FTP server if you only use SFTP etc.
Remember it's the *enabled services* that constitute the majority of the resource usage on your server, not the control panel.