I would not do it. Unless you want to monitor cache stats and make sure that all content has been already written.
It only takes time when you restart it. Just wait first time. Then it can run for days or weeks without any delays.
You can try to speed up mega by using their cmd client and connecting rclone to it via webdav - many people report that it is much faster. It was discussed on the forum many times - you can easy find some threads covering it, e.g.: