by Alain Raap.
@Ken I also tried this option, to make a backup with a Moodle instance on the database server. It looked like it wasn't much faster, and I also see that writing the course-files to the filesystem is slow in my opinion. What is your speed when writing to disk in the temporary folder of Moodle? And did you tweak any configuration settings for this backup configuration (database or PHP)?
Just a tip before you try to configure/test this, if you're using a caching server (like Memcache or Redis) that's not installed on your database server, remove the caching server in the plugin configuration settings (Plugins -> Caching -> configuration in Admin). This will prevent errors in your PHP error log. Otherwise the backup script won't work.